diff --git a/packages/create-release-branch/CHANGELOG.md b/packages/create-release-branch/CHANGELOG.md
index ad4e2d3..8e00660 100644
--- a/packages/create-release-branch/CHANGELOG.md
+++ b/packages/create-release-branch/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Show colors and progress spinners in the CLI output ([#154](https://github.com/MetaMask/release-tools/pull/154))
 - Show the CLI output in one block, with a spinner for long steps and the output of a failing Yarn step ([#159](https://github.com/MetaMask/release-tools/pull/159))
+- Show errors without a stack trace (set `DEBUG=create-release-branch:*` to see it), with their causes, and list release spec problems by line and package ([#160](https://github.com/MetaMask/release-tools/pull/160))
 
 ### Fixed
 
diff --git a/packages/create-release-branch/src/cli.ts b/packages/create-release-branch/src/cli.ts
index 41dd9b9..e1dfdb3 100644
--- a/packages/create-release-branch/src/cli.ts
+++ b/packages/create-release-branch/src/cli.ts
@@ -1,7 +1,7 @@
-import util from 'util';
-
 import { main } from './cli/main.js';
 import { createCliOutput } from './core/cli-output.js';
+import { describeError } from './core/user-facing-error.js';
+import { debug } from './utils/misc-utils.js';
 
 /**
  * The entrypoint to this tool.
@@ -16,8 +16,13 @@ async function cli(): Promise<void> {
 }
 
 cli().catch((error) => {
-  createCliOutput({ stdout: process.stdout, stderr: process.stderr }).error(
-    `${util.inspect(error)}\n`,
-  );
+  const output = createCliOutput({
+    stdout: process.stdout,
+    stderr: process.stderr,
+  });
+  const { title, lines } = describeError(error, output.format, {
+    debug: debug.enabled,
+  });
+  output.failure(title, lines);
   process.exitCode = 1;
 });
diff --git a/packages/create-release-branch/src/core/cli-output.test.ts b/packages/create-release-branch/src/core/cli-output.test.ts
index fcc1af9..c869eef 100644
--- a/packages/create-release-branch/src/core/cli-output.test.ts
+++ b/packages/create-release-branch/src/core/cli-output.test.ts
@@ -1,5 +1,6 @@
 import {
   S_BAR,
+  S_BAR_END,
   S_ERROR,
   S_INFO,
   S_STEP_SUBMIT,
@@ -8,7 +9,7 @@ import {
   spinner,
   taskLog,
 } from '@clack/prompts';
-import { stripVTControlCharacters } from 'node:util';
+import { stripVTControlCharacters, styleText } from 'node:util';
 import { MockWritable } from 'stdio-mock';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
@@ -408,6 +409,75 @@ describe('cli-output', () => {
       expect(taskLog).not.toHaveBeenCalled();
     });
 
+    it('failure writes the title, the lines, and the cancel line to stderr', () => {
+      const stdout = new MockWritable();
+      const stderr = new MockWritable();
+      const output = createCliOutput({ stdout, stderr });
+
+      output.failure('Something failed', ['Line 1', '', 'Line 2']);
+
+      expect(textOf(stderr)).toBe(
+        [
+          logLine(S_ERROR, 'Something failed'),
+          `${S_BAR}\n${S_BAR}  Line 1\n${S_BAR}\n${S_BAR}  Line 2\n${S_BAR}\n`,
+          `${S_BAR_END}  The release did not finish.\n\n`,
+        ].join(''),
+      );
+      expect(stdout.data()).toStrictEqual([]);
+    });
+
+    it('failure writes a gutter line before the closing line when there are no lines', () => {
+      const stdout = new MockWritable();
+      const stderr = new MockWritable();
+      const output = createCliOutput({ stdout, stderr });
+
+      output.failure('Something failed', []);
+
+      expect(textOf(stderr)).toBe(
+        [
+          logLine(S_ERROR, 'Something failed'),
+          `${S_BAR}\n`,
+          `${S_BAR_END}  The release did not finish.\n\n`,
+        ].join(''),
+      );
+    });
+
+    it('failure keeps the gutter on every line of a multi-line entry', () => {
+      const stdout = new MockWritable();
+      const stderr = new MockWritable();
+      const output = createCliOutput({ stdout, stderr });
+
+      output.failure('Something failed', ['Line 1\nLine 2']);
+
+      expect(textOf(stderr)).toBe(
+        [
+          logLine(S_ERROR, 'Something failed'),
+          `${S_BAR}\n${S_BAR}  Line 1\n${S_BAR}  Line 2\n${S_BAR}\n`,
+          `${S_BAR_END}  The release did not finish.\n\n`,
+        ].join(''),
+      );
+    });
+
+    it('formats names and dim text for stderr only when stderr is styled', () => {
+      const styled = createCliOutput({
+        stdout: new MockWritable(),
+        stderr: buildTerminalStream(),
+      });
+      const plain = createCliOutput({
+        stdout: buildTerminalStream(),
+        stderr: new MockWritable(),
+      });
+
+      expect(styled.format.name('a')).toBe(
+        styleText('cyan', 'a', { validateStream: false }),
+      );
+      expect(styled.format.dim('a')).toBe(
+        styleText('dim', 'a', { validateStream: false }),
+      );
+      expect(plain.format.name('a')).toBe('a');
+      expect(plain.format.dim('a')).toBe('a');
+    });
+
     it.each([
       { keyName: 'Ctrl+C', input: '\u0003', key: { ctrl: true, name: 'c' } },
       {
diff --git a/packages/create-release-branch/src/core/cli-output.ts b/packages/create-release-branch/src/core/cli-output.ts
index fb2aeaa..8456a4f 100644
--- a/packages/create-release-branch/src/core/cli-output.ts
+++ b/packages/create-release-branch/src/core/cli-output.ts
@@ -1,4 +1,4 @@
-import { log, spinner, taskLog } from '@clack/prompts';
+import { cancel, log, spinner, taskLog } from '@clack/prompts';
 import { Writable } from 'node:stream';
 import { stripVTControlCharacters, styleText } from 'node:util';
 
@@ -13,6 +13,10 @@ import { stripVTControlCharacters, styleText } from 'node:util';
  * out.
  * @property warn - Writes a warning to standard error.
  * @property error - Writes an error to standard error.
+ * @property failure - Writes the error that stopped the run, with lines of
+ * details, and ends the output, to standard error.
+ * @property format - Styles parts of the text for standard error: `name` for
+ * names, such as package names, and `dim` for secondary text.
  * @property step - Runs a long-running action and returns its result.
  * @property task - Runs a long-running action that prints lines of output,
  * such as a command, and returns its result. The lines are shown only while
@@ -23,6 +27,8 @@ export type CliOutput = {
   success(text: string): void;
   warn(text: string): void;
   error(text: string): void;
+  failure(title: string, lines: string[]): void;
+  format: { name(text: string): string; dim(text: string): string };
   step<Result>(label: string, run: () => Promise<Result>): Promise<Result>;
   task<Result>(
     label: string,
@@ -185,6 +191,12 @@ export function createCliOutput({
 }): CliOutput {
   const toStdout = { output: styled.stdout ? stdout : withoutColors(stdout) };
   const toStderr = { output: styled.stderr ? stderr : withoutColors(stderr) };
+  const format = {
+    name: (text: string): string =>
+      styled.stderr ? styleText('cyan', text, { stream: stderr }) : text,
+    dim: (text: string): string =>
+      styled.stderr ? styleText('dim', text, { stream: stderr }) : text,
+  };
 
   return {
     info(text) {
@@ -199,6 +211,15 @@ export function createCliOutput({
     error(text) {
       log.error(trimTrailingNewlines(text), toStderr);
     },
+    failure(title, lines) {
+      const details = lines.flatMap((line) => line.split('\n'));
+      log.error(title, toStderr);
+      // clack writes one gutter line before the details, so an empty entry
+      // after them adds the same gutter line before the closing line.
+      log.message(details.length > 0 ? [...details, ''] : [], toStderr);
+      cancel('The release did not finish.', toStderr);
+    },
+    format,
     async step(label, run) {
       if (!animate) {
         try {
@@ -236,10 +257,7 @@ export function createCliOutput({
           return result;
         } catch (error) {
           log.error(label, toStderr);
-          log.message(
-            lines.map((line) => styleText('dim', line, { stream: stderr })),
-            toStderr,
-          );
+          log.message(lines.map(format.dim), toStderr);
           throw error;
         }
       }
diff --git a/packages/create-release-branch/src/core/release-rules.test.ts b/packages/create-release-branch/src/core/release-rules.test.ts
index afe3090..3bf8bc2 100644
--- a/packages/create-release-branch/src/core/release-rules.test.ts
+++ b/packages/create-release-branch/src/core/release-rules.test.ts
@@ -10,6 +10,7 @@ import {
   IncrementableVersionParts,
   normalizeReleaseChoices,
 } from './release-rules.js';
+import type { ReleaseChoices } from './release-rules.js';
 
 describe('release-rules', () => {
   describe('checkReleaseChoices', () => {
@@ -52,18 +53,10 @@ describe('release-rules', () => {
       expect(checkReleaseChoices(project, { a: 'major' })).toStrictEqual({
         errors: [
           {
-            message: `
-The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
-
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-`.trim(),
+            packageName: 'a',
+            problem:
+              'has a major bump, but its direct dependents are not in the release spec: b',
+            hint: 'Add them to the release spec, or set them to intentionally-skip.',
           },
         ],
         dependencyFindings: {
@@ -125,18 +118,163 @@ The following direct dependents of package 'a', which is being released with a m
         checkReleaseChoices(project, { a: 'asdf', b: 'minor' }).errors,
       ).toStrictEqual([
         {
-          message: [
-            '"asdf" is not a valid version specifier for package "a"',
-            '(must be "major", "minor", or "patch"; or a version string with major, minor, and patch parts, such as "1.2.3")',
-          ],
+          packageName: 'a',
           entryIndex: 0,
+          problem: '"asdf" is not a valid version specifier',
+          hint: 'Use major, minor, patch, or a version like 1.2.3.',
         },
         {
-          message: '"b" is not a package in the project',
+          packageName: 'b',
           entryIndex: 1,
+          problem: 'is not a package in the project',
+          hint: 'Check the name, or remove the line.',
         },
       ]);
     });
+
+    it('reports an unknown package with an exact version only as unknown', () => {
+      const project = buildMockProject({
+        workspacePackages: {
+          a: buildMockPackage('a', '1.0.0'),
+        },
+      });
+
+      expect(checkReleaseChoices(project, { b: '1.2.3' }).errors).toStrictEqual(
+        [
+          {
+            packageName: 'b',
+            entryIndex: 0,
+            problem: 'is not a package in the project',
+            hint: 'Check the name, or remove the line.',
+          },
+        ],
+      );
+    });
+
+    it.each([
+      {
+        rule: 'an unknown package',
+        workspacePackages: { a: buildMockPackage('a', '1.0.0') },
+        choices: { b: 'minor' },
+        error: {
+          packageName: 'b',
+          entryIndex: 0,
+          problem: 'is not a package in the project',
+          hint: 'Check the name, or remove the line.',
+        },
+      },
+      {
+        rule: 'an invalid version specifier',
+        workspacePackages: { a: buildMockPackage('a', '1.0.0') },
+        choices: { a: 'asdf' },
+        error: {
+          packageName: 'a',
+          entryIndex: 0,
+          problem: '"asdf" is not a valid version specifier',
+          hint: 'Use major, minor, patch, or a version like 1.2.3.',
+        },
+      },
+      {
+        rule: 'a version specifier that is not a string',
+        workspacePackages: { a: buildMockPackage('a', '1.0.0') },
+        choices: { a: { version: '2.0.0' } } as unknown as ReleaseChoices,
+        error: {
+          packageName: 'a',
+          entryIndex: 0,
+          problem: '"{"version":"2.0.0"}" is not a valid version specifier',
+          hint: 'Use major, minor, patch, or a version like 1.2.3.',
+        },
+      },
+      {
+        rule: 'the current version',
+        workspacePackages: { a: buildMockPackage('a', '1.0.0') },
+        choices: { a: '1.0.0' },
+        error: {
+          packageName: 'a',
+          entryIndex: 0,
+          problem: 'is already at version 1.0.0',
+          hint: 'Use a higher version, or major, minor, or patch.',
+        },
+      },
+      {
+        rule: 'a lower version',
+        workspacePackages: { a: buildMockPackage('a', '1.0.0') },
+        choices: { a: '0.9.0' },
+        error: {
+          packageName: 'a',
+          entryIndex: 0,
+          problem: '"0.9.0" is lower than the current version 1.0.0',
+          hint: 'Use a higher version, or major, minor, or patch.',
+        },
+      },
+      {
+        rule: 'missing direct dependents',
+        workspacePackages: {
+          a: buildMockPackage('a', '1.0.0'),
+          b: buildMockPackage('b', {
+            validatedManifest: { dependencies: { a: '1.0.0' } },
+          }),
+          c: buildMockPackage('c', {
+            validatedManifest: { dependencies: { a: '1.0.0' } },
+          }),
+        },
+        choices: { a: 'major' },
+        error: {
+          packageName: 'a',
+          problem:
+            'has a major bump, but its direct dependents are not in the release spec: b, c',
+          hint: 'Add them to the release spec, or set them to intentionally-skip.',
+        },
+      },
+      {
+        rule: 'missing peer dependents',
+        workspacePackages: {
+          a: buildMockPackage('a', '1.0.0'),
+          b: buildMockPackage('b', {
+            validatedManifest: { peerDependencies: { a: '1.0.0' } },
+          }),
+          c: buildMockPackage('c', {
+            validatedManifest: { peerDependencies: { a: '1.0.0' } },
+          }),
+        },
+        choices: { a: 'major' },
+        error: {
+          packageName: 'a',
+          problem:
+            'has a major bump, but its peer dependents are not in the release spec: b, c',
+          hint: 'Add them so they stay compatible, or set them to intentionally-skip if they can wait.',
+        },
+      },
+      {
+        rule: 'missing changed dependencies',
+        workspacePackages: {
+          a: buildMockPackage('a', {
+            validatedManifest: {
+              dependencies: { b: '1.0.0' },
+              peerDependencies: { c: '1.0.0' },
+            },
+          }),
+          b: buildMockPackage('b', { hasChangesSinceLatestRelease: true }),
+          c: buildMockPackage('c', { hasChangesSinceLatestRelease: true }),
+        },
+        choices: { a: 'minor' },
+        error: {
+          packageName: 'a',
+          problem:
+            'depends on packages with unreleased changes that are not in the release spec: b, c',
+          hint: 'Add them to the release spec, or set them to intentionally-skip if they can wait.',
+        },
+      },
+    ])(
+      'reports $rule with its problem and hint',
+      ({ workspacePackages, choices, error }) => {
+        const project = buildMockProject({ workspacePackages });
+
+        expect(checkReleaseChoices(project, choices).errors).toStrictEqual([
+          error,
+        ]);
+      },
+    );
   });
 
   describe('normalizeReleaseChoices', () => {
diff --git a/packages/create-release-branch/src/core/release-rules.ts b/packages/create-release-branch/src/core/release-rules.ts
index 03f61c4..539439a 100644
--- a/packages/create-release-branch/src/core/release-rules.ts
+++ b/packages/create-release-branch/src/core/release-rules.ts
@@ -1,5 +1,4 @@
 import { diff } from 'semver';
-import YAML from 'yaml';
 
 import type { Package } from '../project/package.js';
 import type { Project } from '../project/project.js';
@@ -48,13 +47,17 @@ export type DependencyFinding = {
 /**
  * A problem with the release choices.
  *
- * @property message - The message, as a single string or as separate lines.
+ * @property packageName - The name of the package that the problem is about.
  * @property entryIndex - The index of the choice in `Object.entries(choices)`,
  * for problems that point at a single entry.
+ * @property problem - What is wrong, written to follow the package name.
+ * @property hint - How to fix it.
  */
 export type ReleaseChoiceError = {
-  message: string | string[];
+  packageName?: string;
   entryIndex?: number;
+  problem: string;
+  hint?: string;
 };
 
 /**
@@ -208,29 +211,6 @@ function findCandidateDependencies(
   return [];
 }
 
-/**
- * Builds the YAML example, indented for an error message, that lists the
- * given packages with the "intentionally-skip" directive.
- *
- * @param packageNames - The names of the packages to list.
- * @returns The indented YAML example.
- */
-function buildIntentionallySkipExample(packageNames: string[]): string {
-  return YAML.stringify({
-    packages: packageNames.reduce(
-      (object, packageName) => ({
-        ...object,
-        [packageName]: INTENTIONALLY_SKIP_PACKAGE_DIRECTIVE,
-      }),
-      {},
-    ),
-  })
-    .trim()
-    .split('\n')
-    .map((line) => `    ${line}`)
-    .join('\n');
-}
-
 /**
  * Checks the release choices against the project: the names of the packages,
  * the version specifiers, and the dependencies and dependents that must be
@@ -270,9 +250,12 @@ export function checkReleaseChoices(
 
       if (changedPackage === undefined) {
         errors.push({
-          message: `${JSON.stringify(changedPackageName)} is not a package in the project`,
+          packageName: changedPackageName,
           entryIndex,
+          problem: 'is not a package in the project',
+          hint: 'Check the name, or remove the line.',
         });
+        return;
       }
 
       if (
@@ -282,37 +265,36 @@ export function checkReleaseChoices(
         !isValidSemver(versionSpecifierOrDirective)
       ) {
         errors.push({
-          message: [
-            `${JSON.stringify(versionSpecifierOrDirective)} is not a valid version specifier for package "${changedPackageName}"`,
-            `(must be "major", "minor", or "patch"; or a version string with major, minor, and patch parts, such as "1.2.3")`,
-          ],
+          packageName: changedPackageName,
           entryIndex,
+          problem: `"${
+            typeof versionSpecifierOrDirective === 'string'
+              ? versionSpecifierOrDirective
+              : JSON.stringify(versionSpecifierOrDirective)
+          }" is not a valid version specifier`,
+          hint: 'Use major, minor, patch, or a version like 1.2.3.',
         });
       }
 
       if (isValidSemver(versionSpecifierOrDirective)) {
+        const currentVersion = changedPackage.validatedManifest.version;
         const comparison = new SemVer(versionSpecifierOrDirective).compare(
-          changedPackage.validatedManifest.version,
+          currentVersion,
         );
 
         if (comparison === 0) {
           errors.push({
-            message: [
-              `${JSON.stringify(versionSpecifierOrDirective)} is not a valid version specifier for package "${changedPackageName}"`,
-              `("${changedPackageName}" is already at version "${versionSpecifierOrDirective}")`,
-            ],
+            packageName: changedPackageName,
             entryIndex,
+            problem: `is already at version ${versionSpecifierOrDirective}`,
+            hint: 'Use a higher version, or major, minor, or patch.',
           });
         } else if (comparison < 0) {
           errors.push({
-            message: [
-              `${JSON.stringify(versionSpecifierOrDirective)} is not a valid version specifier for package "${changedPackageName}"`,
-              `("${changedPackageName}" is at a greater version "${String(
-                project.workspacePackages[changedPackageName].validatedManifest
-                  .version,
-              )}")`,
-            ],
+            packageName: changedPackageName,
             entryIndex,
+            problem: `"${versionSpecifierOrDirective}" is lower than the current version ${String(currentVersion)}`,
+            hint: 'Use a higher version, or major, minor, or patch.',
           });
         }
       }
@@ -328,15 +310,9 @@ export function checkReleaseChoices(
 
       if (missingDirectDependentNames.length > 0) {
         errors.push({
-          message: [
-            `The following direct dependents of package '${changedPackageName}', which is being released with a major version bump, are missing from the release spec.`,
-            missingDirectDependentNames
-              .map((dependent) => `  - ${dependent}`)
-              .join('\n'),
-            `  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.`,
-            `  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:`,
-            buildIntentionallySkipExample(missingDirectDependentNames),
-          ].join('\n\n'),
+          packageName: changedPackageName,
+          problem: `has a major bump, but its direct dependents are not in the release spec: ${missingDirectDependentNames.join(', ')}`,
+          hint: 'Add them to the release spec, or set them to intentionally-skip.',
         });
       }
 
@@ -351,15 +327,9 @@ export function checkReleaseChoices(
 
       if (missingPeerDependentNames.length > 0) {
         errors.push({
-          message: [
-            `The following dependents of package '${changedPackageName}', which is being released with a major version bump, are missing from the release spec.`,
-            missingPeerDependentNames
-              .map((dependent) => `  - ${dependent}`)
-              .join('\n'),
-            `  Consider including them in the release spec so that they are compatible with the new '${changedPackageName}' version.`,
-            `  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:`,
-            buildIntentionallySkipExample(missingPeerDependentNames),
-          ].join('\n\n'),
+          packageName: changedPackageName,
+          problem: `has a major bump, but its peer dependents are not in the release spec: ${missingPeerDependentNames.join(', ')}`,
+          hint: 'Add them so they stay compatible, or set them to intentionally-skip if they can wait.',
         });
       }
 
@@ -372,15 +342,9 @@ export function checkReleaseChoices(
 
       if (missingDependencies.length > 0) {
         errors.push({
-          message: [
-            `The following packages, which are dependencies or peer dependencies of the package '${changedPackageName}' being released, are missing from the release spec.`,
-            missingDependencies
-              .map((dependency) => `  - ${dependency}`)
-              .join('\n'),
-            `  These packages may have changes that '${changedPackageName}' relies upon. Consider including them in the release spec.`,
-            `  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:`,
-            buildIntentionallySkipExample(missingDependencies),
-          ].join('\n\n'),
+          packageName: changedPackageName,
+          problem: `depends on packages with unreleased changes that are not in the release spec: ${missingDependencies.join(', ')}`,
+          hint: 'Add them to the release spec, or set them to intentionally-skip if they can wait.',
         });
       }
 
diff --git a/packages/create-release-branch/src/core/release-steps.test.ts b/packages/create-release-branch/src/core/release-steps.test.ts
index a088604..d9964e0 100644
--- a/packages/create-release-branch/src/core/release-steps.test.ts
+++ b/packages/create-release-branch/src/core/release-steps.test.ts
@@ -185,11 +185,10 @@ describe('release-steps', () => {
       expect(result).toStrictEqual({
         errors: [
           {
-            message: [
-              '"foo" is not a valid version specifier for package "a"',
-              '(must be "major", "minor", or "patch"; or a version string with major, minor, and patch parts, such as "1.2.3")',
-            ],
+            packageName: 'a',
             entryIndex: 0,
+            problem: '"foo" is not a valid version specifier',
+            hint: 'Use major, minor, patch, or a version like 1.2.3.',
           },
         ],
         dependencyFindings: {},
@@ -202,7 +201,7 @@ describe('release-steps', () => {
       const project = buildMockProject({
         workspacePackages: { a: buildMockPackage('a', '1.0.0') },
       });
-      const planErrors = [{ message: 'Nothing to release' }];
+      const planErrors = [{ problem: 'Nothing to release' }];
       const plan = vi.fn().mockResolvedValue({ errors: planErrors });
       const mode = buildMockMode({ plan });
 
diff --git a/packages/create-release-branch/src/core/user-facing-error.test.ts b/packages/create-release-branch/src/core/user-facing-error.test.ts
new file mode 100644
index 0000000..cb0e185
--- /dev/null
+++ b/packages/create-release-branch/src/core/user-facing-error.test.ts
@@ -0,0 +1,83 @@
+import { describe, expect, it } from 'vitest';
+
+import type { CliOutput } from './cli-output.js';
+import { describeError, UserFacingError } from './user-facing-error.js';
+
+const format: CliOutput['format'] = {
+  name: (text) => `<${text}>`,
+  dim: (text) => `(${text})`,
+};
+
+class TestError extends UserFacingError {
+  describe(
+    errorFormat: CliOutput['format'],
+  ): ReturnType<UserFacingError['describe']> {
+    return { title: 'Test title', lines: [errorFormat.name('a')] };
+  }
+}
+
+describe('user-facing-error', () => {
+  describe('describeError', () => {
+    it('uses the description of a user-facing error', () => {
+      const error = new TestError('Some message', {
+        cause: new Error('Some cause'),
+      });
+
+      expect(describeError(error, format, { debug: true })).toStrictEqual({
+        title: 'Test title',
+        lines: ['<a>'],
+      });
+    });
+
+    it('prints causes and hides the stack trace', () => {
+      const error = new Error('Could not read file\nmore details', {
+        cause: new Error('Permission denied', { cause: 'EACCES' }),
+      });
+
+      expect(describeError(error, format, { debug: false })).toStrictEqual({
+        title: 'Could not read file',
+        lines: [
+          'more details',
+          'Caused by: Permission denied',
+          'Caused by: EACCES',
+        ],
+      });
+    });
+
+    it('prints the stack trace when debugging is on', () => {
+      const error = new Error('Something failed', {
+        cause: new Error('Some cause'),
+      });
+      error.stack = 'Error: Something failed\n    at line 1\n    at line 2';
+
+      expect(describeError(error, format, { debug: true })).toStrictEqual({
+        title: 'Something failed',
+        lines: [
+          'Caused by: Some cause',
+          '',
+          'Error: Something failed',
+          '    at line 1',
+          '    at line 2',
+        ],
+      });
+    });
+
+    it('stops at a cause that is already in the chain', () => {
+      const error = new Error('Something failed');
+      const cause = new Error('Some cause', { cause: error });
+      error.cause = cause;
+
+      expect(describeError(error, format, { debug: false })).toStrictEqual({
+        title: 'Something failed',
+        lines: ['Caused by: Some cause'],
+      });
+    });
+
+    it('describes a value that is not an error', () => {
+      expect(describeError('oops', format, { debug: true })).toStrictEqual({
+        title: 'oops',
+        lines: [],
+      });
+    });
+  });
+});
diff --git a/packages/create-release-branch/src/core/user-facing-error.ts b/packages/create-release-branch/src/core/user-facing-error.ts
new file mode 100644
index 0000000..4892260
--- /dev/null
+++ b/packages/create-release-branch/src/core/user-facing-error.ts
@@ -0,0 +1,65 @@
+import type { CliOutput } from './cli-output.js';
+
+/**
+ * An error that describes itself to the user, with a title and lines of
+ * details, instead of being printed with its message, causes, and stack.
+ */
+export abstract class UserFacingError extends Error {
+  /**
+   * Describes the error to the user.
+   *
+   * @param format - Styles parts of the text.
+   * @returns The title and the lines of details.
+   */
+  abstract describe(format: CliOutput['format']): {
+    title: string;
+    lines: string[];
+  };
+}
+
+/**
+ * Gets the message of an error, or the text of a value that is not an error.
+ *
+ * @param error - The error.
+ * @returns The message.
+ */
+function messageOf(error: unknown): string {
+  return error instanceof Error ? error.message : String(error);
+}
+
+/**
+ * Describes an error to the user. A `UserFacingError` describes itself. Any
+ * other error is described by its message, then one `Caused by` line for each
+ * error in its chain of causes, then its stack trace when debugging.
+ *
+ * @param error - The error.
+ * @param format - Styles parts of the text.
+ * @param options - The options.
+ * @param options.debug - Whether to include the stack trace.
+ * @returns The title and the lines of details.
+ */
+export function describeError(
+  error: unknown,
+  format: CliOutput['format'],
+  { debug }: { debug: boolean },
+): { title: string; lines: string[] } {
+  if (error instanceof UserFacingError) {
+    return error.describe(format);
+  }
+
+  const [title, ...lines] = messageOf(error).split('\n');
+
+  const seen = new Set<unknown>([error]);
+  let cause = error instanceof Error ? error.cause : undefined;
+  while (cause !== undefined && !seen.has(cause)) {
+    seen.add(cause);
+    lines.push(`Caused by: ${messageOf(cause)}`);
+    cause = cause instanceof Error ? cause.cause : undefined;
+  }
+
+  if (debug && error instanceof Error && error.stack !== undefined) {
+    lines.push('', ...error.stack.split('\n'));
+  }
+
+  return { title, lines };
+}
diff --git a/packages/create-release-branch/src/frontends/editor/editor-front-end.test.ts b/packages/create-release-branch/src/frontends/editor/editor-front-end.test.ts
index 16ec854..bd69df9 100644
--- a/packages/create-release-branch/src/frontends/editor/editor-front-end.test.ts
+++ b/packages/create-release-branch/src/frontends/editor/editor-front-end.test.ts
@@ -1093,8 +1093,10 @@ describe('editor-front-end', () => {
             {
               errors: [
                 {
-                  message: '"foo" is not a package in the project',
+                  packageName: 'foo',
                   entryIndex: 0,
+                  problem: 'is not a package in the project',
+                  hint: 'Check the name, or remove the line.',
                 },
               ],
               dependencyFindings: {},
diff --git a/packages/create-release-branch/src/frontends/editor/release-specification.test.ts b/packages/create-release-branch/src/frontends/editor/release-specification.test.ts
index 059597a..c3ee874 100644
--- a/packages/create-release-branch/src/frontends/editor/release-specification.test.ts
+++ b/packages/create-release-branch/src/frontends/editor/release-specification.test.ts
@@ -18,6 +18,7 @@ import type { Project } from '../../project/project.js';
 import * as miscUtils from '../../utils/misc-utils.js';
 import {
   generateReleaseSpecificationTemplateForMonorepo,
+  ReleaseSpecificationError,
   waitForUserToEditReleaseSpecification,
   validateReleaseSpecification as validateReleaseSpecificationWithCheck,
 } from './release-specification.js';
@@ -404,9 +405,13 @@ packages:
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           expect.objectContaining({
-            message: expect.stringMatching(
-              /^Your release spec does not appear to be valid YAML\.\n/u,
-            ) as string,
+            problems: [
+              {
+                problem: 'is not valid YAML',
+                hint: 'Fix the syntax: Missing closing "quote at line 1, column 10',
+              },
+            ],
+            specPath: releaseSpecificationPath,
             cause: expect.objectContaining({
               message: expect.stringMatching(
                 /^Missing closing "quote/u,
@@ -432,7 +437,14 @@ packages:
         await expect(
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
-          /^Your release spec could not be processed because it needs to be an object/u,
+          expect.objectContaining({
+            problems: [
+              {
+                problem:
+                  'needs a packages object, where each key is a package name and each value is a version specifier',
+              },
+            ],
+          }),
         );
       });
     });
@@ -452,7 +464,14 @@ packages:
         await expect(
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
-          /^Your release spec could not be processed because it needs to be an object/u,
+          expect.objectContaining({
+            problems: [
+              {
+                problem:
+                  'needs a packages object, where each key is a package name and each value is a version specifier',
+              },
+            ],
+          }),
         );
       });
     });
@@ -481,14 +500,22 @@ packages:
         await expect(
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
-          new RegExp(
-            [
-              '^Your release spec could not be processed due to the following issues:\n',
-              '\\* Line 2: "foo" is not a package in the project',
-              '\\* Line 3: "bar" is not a package in the project',
-            ].join('\n'),
-            'u',
-          ),
+          expect.objectContaining({
+            problems: [
+              {
+                lineNumber: 2,
+                packageName: 'foo',
+                problem: 'is not a package in the project',
+                hint: 'Check the name, or remove the line.',
+              },
+              {
+                lineNumber: 3,
+                packageName: 'bar',
+                problem: 'is not a package in the project',
+                hint: 'Check the name, or remove the line.',
+              },
+            ],
+          }),
         );
       });
     });
@@ -518,16 +545,22 @@ packages:
         await expect(
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
-          new RegExp(
-            [
-              '^Your release spec could not be processed due to the following issues:\n',
-              '\\* Line 2: "asdflksdaf" is not a valid version specifier for package "a"',
-              '          \\(must be "major", "minor", or "patch"; or a version string with major, minor, and patch parts, such as "1\\.2\\.3"\\)',
-              '\\* Line 3: "1.2\\.\\.\\.3\\." is not a valid version specifier for package "b"',
-              '          \\(must be "major", "minor", or "patch"; or a version string with major, minor, and patch parts, such as "1\\.2\\.3"\\)',
-            ].join('\n'),
-            'u',
-          ),
+          expect.objectContaining({
+            problems: [
+              {
+                lineNumber: 2,
+                packageName: 'a',
+                problem: '"asdflksdaf" is not a valid version specifier',
+                hint: 'Use major, minor, patch, or a version like 1.2.3.',
+              },
+              {
+                lineNumber: 3,
+                packageName: 'b',
+                problem: '"1.2...3." is not a valid version specifier',
+                hint: 'Use major, minor, patch, or a version like 1.2.3.',
+              },
+            ],
+          }),
         );
       });
     });
@@ -557,14 +590,22 @@ packages:
         await expect(
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
-          `
-Your release spec could not be processed due to the following issues:
-
-* Line 2: "1.2.3" is not a valid version specifier for package "a"
-          ("a" is already at version "1.2.3")
-* Line 3: "4.5.6" is not a valid version specifier for package "b"
-          ("b" is already at version "4.5.6")
-`.trim(),
+          expect.objectContaining({
+            problems: [
+              {
+                lineNumber: 2,
+                packageName: 'a',
+                problem: 'is already at version 1.2.3',
+                hint: 'Use a higher version, or major, minor, or patch.',
+              },
+              {
+                lineNumber: 3,
+                packageName: 'b',
+                problem: 'is already at version 4.5.6',
+                hint: 'Use a higher version, or major, minor, or patch.',
+              },
+            ],
+          }),
         );
       });
     });
@@ -594,14 +635,22 @@ Your release spec could not be processed due to the following issues:
         await expect(
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
-          `
-Your release spec could not be processed due to the following issues:
-
-* Line 2: "1.2.2" is not a valid version specifier for package "a"
-          ("a" is at a greater version "1.2.3")
-* Line 3: "4.5.5" is not a valid version specifier for package "b"
-          ("b" is at a greater version "4.5.6")
-`.trim(),
+          expect.objectContaining({
+            problems: [
+              {
+                lineNumber: 2,
+                packageName: 'a',
+                problem: '"1.2.2" is lower than the current version 1.2.3',
+                hint: 'Use a higher version, or major, minor, or patch.',
+              },
+              {
+                lineNumber: 3,
+                packageName: 'b',
+                problem: '"4.5.5" is lower than the current version 4.5.6',
+                hint: 'Use a higher version, or major, minor, or patch.',
+              },
+            ],
+          }),
         );
       });
     });
@@ -640,21 +689,13 @@ Your release spec could not be processed due to the following issues:
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that they are compatible with the new 'a' version.
-
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
+The release spec has 1 problem:
 
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its peer dependents are not in the release spec: b
+  Add them so they stay compatible, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -695,21 +736,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that they are compatible with the new 'a' version.
+The release spec has 1 problem:
 
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its peer dependents are not in the release spec: b
+  Add them so they stay compatible, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -750,21 +783,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that they are compatible with the new 'a' version.
+The release spec has 1 problem:
 
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its peer dependents are not in the release spec: b
+  Add them so they stay compatible, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -805,21 +830,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that they are compatible with the new 'a' version.
+The release spec has 1 problem:
 
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its peer dependents are not in the release spec: b
+  Add them so they stay compatible, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -861,21 +878,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that they are compatible with the new 'a' version.
+The release spec has 1 problem:
 
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its peer dependents are not in the release spec: b
+  Add them so they stay compatible, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -917,21 +926,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
+The release spec has 1 problem:
 
-  Consider including them in the release spec so that they are compatible with the new 'a' version.
-
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its peer dependents are not in the release spec: b
+  Add them so they stay compatible, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -973,21 +974,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
+The release spec has 1 problem:
 
-  Consider including them in the release spec so that they are compatible with the new 'a' version.
-
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its peer dependents are not in the release spec: b
+  Add them so they stay compatible, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1029,21 +1022,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
+The release spec has 1 problem:
 
-  - b
-
-  Consider including them in the release spec so that they are compatible with the new 'a' version.
-
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its peer dependents are not in the release spec: b
+  Add them so they stay compatible, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1084,21 +1069,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
-
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
+The release spec has 1 problem:
 
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its direct dependents are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1139,21 +1116,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
+The release spec has 1 problem:
 
-* The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
-
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its direct dependents are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1194,21 +1163,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
-
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
+The release spec has 1 problem:
 
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its direct dependents are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1249,21 +1210,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
+The release spec has 1 problem:
 
-* The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
-
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its direct dependents are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1305,21 +1258,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
-
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
+The release spec has 1 problem:
 
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its direct dependents are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1361,21 +1306,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
-
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
+The release spec has 1 problem:
 
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its direct dependents are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1417,21 +1354,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
+The release spec has 1 problem:
 
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its direct dependents are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1473,21 +1402,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following direct dependents of package 'a', which is being released with a major version bump, are missing from the release spec.
-
-  - b
-
-  Consider including them in the release spec so that the dependency tree of consuming projects can be kept small.
+The release spec has 1 problem:
 
-  If you do not want to do this, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  has a major bump, but its direct dependents are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1708,21 +1629,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following packages, which are dependencies or peer dependencies of the package 'a' being released, are missing from the release spec.
-
-  - b
+The release spec has 1 problem:
 
-  These packages may have changes that 'a' relies upon. Consider including them in the release spec.
-
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  depends on packages with unreleased changes that are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1763,21 +1676,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following packages, which are dependencies or peer dependencies of the package 'a' being released, are missing from the release spec.
-
-  - b
+The release spec has 1 problem:
 
-  These packages may have changes that 'a' relies upon. Consider including them in the release spec.
-
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  depends on packages with unreleased changes that are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1819,21 +1724,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following packages, which are dependencies or peer dependencies of the package 'a' being released, are missing from the release spec.
-
-  - b
+The release spec has 1 problem:
 
-  These packages may have changes that 'a' relies upon. Consider including them in the release spec.
-
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  depends on packages with unreleased changes that are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -1875,21 +1772,13 @@ ${releaseSpecificationPath}
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
           `
-Your release spec could not be processed due to the following issues:
-
-* The following packages, which are dependencies or peer dependencies of the package 'a' being released, are missing from the release spec.
-
-  - b
+The release spec has 1 problem:
 
-  These packages may have changes that 'a' relies upon. Consider including them in the release spec.
-
-  If you are ABSOLUTELY SURE these packages are safe to omit, however, and want to postpone the release of a package, then list it with a directive of "intentionally-skip". For example:
-
-    packages:
-      b: intentionally-skip
-
-The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.
+a
+  depends on packages with unreleased changes that are not in the release spec: b
+  Add them to the release spec, or set them to intentionally-skip if they can wait.
 
+Fix the release spec and run the tool again. It was kept at:
 ${releaseSpecificationPath}
 `.trim(),
         );
@@ -2076,7 +1965,7 @@ ${releaseSpecificationPath}
       });
     });
 
-    it("keeps today's line numbers for a generated template", async () => {
+    it("keeps today's line numbers in the new layout", async () => {
       await withSandbox(async (sandbox) => {
         const project = buildMockProject({
           workspacePackages: {
@@ -2100,9 +1989,92 @@ ${releaseSpecificationPath}
         await expect(
           validateReleaseSpecification(project, releaseSpecificationPath),
         ).rejects.toThrow(
-          '* Line 29: "foo" is not a valid version specifier for package "a"',
+          [
+            'Line 29  a',
+            '         "foo" is not a valid version specifier',
+            '         Use major, minor, patch, or a version like 1.2.3.',
+          ].join('\n'),
         );
       });
     });
   });
+
+  describe('ReleaseSpecificationError', () => {
+    const format = {
+      name: (text: string): string => `<${text}>`,
+      dim: (text: string): string => `(${text})`,
+    };
+
+    it('describes each problem with its line, package, problem, and hint', () => {
+      const error = new ReleaseSpecificationError({
+        problems: [
+          {
+            lineNumber: 7,
+            packageName: 'a',
+            problem: '"foo" is not a valid version specifier',
+            hint: 'Use major, minor, patch, or a version like 1.2.3.',
+          },
+          {
+            packageName: 'b',
+            problem: 'has a major bump',
+            hint: 'Add them.',
+          },
+          {
+            problem: 'is not valid YAML',
+            hint: 'Fix the syntax: Missing closing "quote at line 1, column 10',
+          },
+        ],
+        specPath: '/path/to/RELEASE_SPEC.yml',
+      });
+
+      expect(error.describe(format)).toStrictEqual({
+        title: 'The release spec has 3 problems:',
+        lines: [
+          'Line 7  <a>',
+          '        "foo" is not a valid version specifier',
+          '        (Use major, minor, patch, or a version like 1.2.3.)',
+          '',
+          '<b>',
+          '  has a major bump',
+          '  (Add them.)',
+          '',
+          'The release spec',
+          '  is not valid YAML',
+          '  (Fix the syntax: Missing closing "quote at line 1, column 10)',
+          '',
+          'Fix the release spec and run the tool again. It was kept at:',
+          '(/path/to/RELEASE_SPEC.yml)',
+        ],
+      });
+    });
+
+    it('uses the singular for one problem', () => {
+      const error = new ReleaseSpecificationError({
+        problems: [{ packageName: 'a', problem: 'is not a package' }],
+        specPath: '/path/to/RELEASE_SPEC.yml',
+      });
+
+      expect(error.describe(format)).toStrictEqual({
+        title: 'The release spec has 1 problem:',
+        lines: [
+          '<a>',
+          '  is not a package',
+          '',
+          'Fix the release spec and run the tool again. It was kept at:',
+          '(/path/to/RELEASE_SPEC.yml)',
+        ],
+      });
+      expect(error.message).toBe(
+        [
+          'The release spec has 1 problem:',
+          '',
+          'a',
+          '  is not a package',
+          '',
+          'Fix the release spec and run the tool again. It was kept at:',
+          '/path/to/RELEASE_SPEC.yml',
+        ].join('\n'),
+      );
+    });
+  });
 });
diff --git a/packages/create-release-branch/src/frontends/editor/release-specification.ts b/packages/create-release-branch/src/frontends/editor/release-specification.ts
index fc98976..6d996cf 100644
--- a/packages/create-release-branch/src/frontends/editor/release-specification.ts
+++ b/packages/create-release-branch/src/frontends/editor/release-specification.ts
@@ -1,12 +1,14 @@
 import YAML from 'yaml';
 
 import type { Candidate } from '../../core/candidates.js';
+import type { CliOutput } from '../../core/cli-output.js';
 import type { ModeName } from '../../core/mode.js';
 import { SKIP_PACKAGE_DIRECTIVE } from '../../core/release-rules.js';
 import type {
   ReleaseChoiceError,
   ReleaseChoices,
 } from '../../core/release-rules.js';
+import { UserFacingError } from '../../core/user-facing-error.js';
 import { readFile } from '../../utils/fs.js';
 import {
   debug,
@@ -75,6 +77,88 @@ const TEMPLATE_TEXT_BY_MODE: Record<ModeName, TemplateText> = {
   },
 };
 
+/**
+ * A problem in the release spec.
+ *
+ * @property lineNumber - The line of the release spec that has the problem.
+ * @property packageName - The name of the package that has the problem.
+ * @property problem - What is wrong, written to follow the package name, or
+ * "The release spec" if there is no package.
+ * @property hint - How to fix it.
+ */
+export type ReleaseSpecificationProblem = {
+  lineNumber?: number;
+  packageName?: string;
+  problem: string;
+  hint?: string;
+};
+
+/**
+ * The problems in a release spec that the user has edited. The release spec
+ * is kept, so the user can fix it and run the tool again.
+ */
+export class ReleaseSpecificationError extends UserFacingError {
+  problems: ReleaseSpecificationProblem[];
+
+  specPath: string;
+
+  /**
+   * Creates the error.
+   *
+   * @param args - The arguments.
+   * @param args.problems - The problems in the release spec.
+   * @param args.specPath - The path to the release spec.
+   * @param options - The options.
+   * @param options.cause - The error that caused the problems.
+   */
+  constructor(
+    {
+      problems,
+      specPath,
+    }: { problems: ReleaseSpecificationProblem[]; specPath: string },
+    options?: { cause: unknown },
+  ) {
+    super(undefined, options);
+    this.problems = problems;
+    this.specPath = specPath;
+    const { title, lines } = this.describe({
+      name: (text) => text,
+      dim: (text) => text,
+    });
+    this.message = [title, '', ...lines].join('\n');
+  }
+
+  describe(format: CliOutput['format']): { title: string; lines: string[] } {
+    const count = this.problems.length;
+    const title = `The release spec has ${count} ${count === 1 ? 'problem' : 'problems'}:`;
+    const problemLines = this.problems.map(
+      ({ lineNumber, packageName, problem, hint }) => {
+        const subject =
+          packageName === undefined
+            ? 'The release spec'
+            : format.name(packageName);
+        const linePrefix =
+          lineNumber === undefined ? '' : `Line ${lineNumber}  `;
+        const indent = ' '.repeat(Math.max(linePrefix.length, 2));
+        return [
+          `${linePrefix}${subject}`,
+          `${indent}${problem}`,
+          ...(hint === undefined ? [] : [`${indent}${format.dim(hint)}`]),
+        ];
+      },
+    );
+
+    return {
+      title,
+      lines: [
+        ...problemLines.flatMap((lines) => [...lines, '']),
+        'Fix the release spec and run the tool again. It was kept at:',
+        format.dim(this.specPath),
+      ],
+    };
+  }
+}
+
 /**
  * Generates a skeleton for a release specification, which describes how a
  * project should be updated.
@@ -156,7 +240,7 @@ export async function waitForUserToEditReleaseSpecification(
  * @param check - Checks the release choices. It returns the plan only when
  * there are no errors.
  * @returns The plan that `check` returns.
- * @throws If there are any issues with the file.
+ * @throws A `ReleaseSpecificationError` if there are any issues with the file.
  */
 export async function validateReleaseSpecification<Plan>(
   releaseSpecificationPath: string,
@@ -173,22 +257,24 @@ export async function validateReleaseSpecification<Plan>(
     packages: ReleaseChoices;
   };
 
-  const afterwordForAllErrorMessages = [
-    "The release spec file has been retained for you to edit again and make the necessary fixes. Once you've done this, re-run this tool.",
-    releaseSpecificationPath,
-  ].join('\n\n');
-
   try {
     unvalidatedReleaseSpecification = YAML.parse(
       releaseSpecificationContents,
     ) as { packages: ReleaseChoices };
   } catch (error) {
-    throw wrapError(
-      [
-        'Your release spec does not appear to be valid YAML.',
-        afterwordForAllErrorMessages,
-      ].join('\n\n'),
-      error,
+    // Typecast: `YAML.parse` throws a `YAMLParseError`, which is an `Error`.
+    const [firstLineOfMessage] = (error as Error).message.split('\n');
+    throw new ReleaseSpecificationError(
+      {
+        problems: [
+          {
+            problem: 'is not valid YAML',
+            hint: `Fix the syntax: ${firstLineOfMessage.replace(/:$/u, '')}`,
+          },
+        ],
+        specPath: releaseSpecificationPath,
+      },
+      { cause: error },
     );
   }
 
@@ -196,54 +282,28 @@ export async function validateReleaseSpecification<Plan>(
     !isObject(unvalidatedReleaseSpecification) ||
     unvalidatedReleaseSpecification.packages === undefined
   ) {
-    const message = [
-      `Your release spec could not be processed because it needs to be an object with a \`packages\` property. The value of \`packages\` must itself be an object, where each key is a workspace package in the project and each value is a version specifier ("major", "minor", or "patch"; or a version string with major, minor, and patch parts, such as "1.2.3").`,
-      `Here is the parsed version of the file you provided:`,
-      JSON.stringify(unvalidatedReleaseSpecification, null, 2),
-      afterwordForAllErrorMessages,
-    ].join('\n\n');
-    throw new Error(message);
+    throw new ReleaseSpecificationError({
+      problems: [
+        {
+          problem:
+            'needs a packages object, where each key is a package name and each value is a version specifier',
+        },
+      ],
+      specPath: releaseSpecificationPath,
+    });
   }
 
   const result = await check(unvalidatedReleaseSpecification.packages);
 
   if (!('plan' in result)) {
-    const errors = result.errors.map(({ message, entryIndex }) => ({
-      message,
-      lineNumber:
+    throw new ReleaseSpecificationError({
+      problems: result.errors.map(({ entryIndex, ...problem }) =>
         entryIndex === undefined
-          ? undefined
-          : indexOfFirstUsableLine + entryIndex + 2,
-    }));
-    const message = [
-      'Your release spec could not be processed due to the following issues:',
-      errors
-        .flatMap((error) => {
-          const itemPrefix = '* ';
-
-          if (error.lineNumber === undefined) {
-            return `${itemPrefix}${String(error.message)}`;
-          }
-
-          const lineNumberPrefix = `Line ${error.lineNumber}: `;
-
-          if (Array.isArray(error.message)) {
-            return [
-              `${itemPrefix}${lineNumberPrefix}${error.message[0]}`,
-              ...error.message.slice(1).map((line) => {
-                const indentedLineLength =
-                  itemPrefix.length + lineNumberPrefix.length + line.length;
-                return line.padStart(indentedLineLength, ' ');
-              }),
-            ];
-          }
-
-          return `${itemPrefix}${lineNumberPrefix}${error.message}`;
-        })
-        .join('\n'),
-      afterwordForAllErrorMessages,
-    ].join('\n\n');
-    throw new Error(message);
+          ? problem
+          : { lineNumber: indexOfFirstUsableLine + entryIndex + 2, ...problem },
+      ),
+      specPath: releaseSpecificationPath,
+    });
   }
 
   return result.plan;
diff --git a/packages/create-release-branch/src/frontends/ui/server.test.ts b/packages/create-release-branch/src/frontends/ui/server.test.ts
index 33f191e..a8e065e 100644
--- a/packages/create-release-branch/src/frontends/ui/server.test.ts
+++ b/packages/create-release-branch/src/frontends/ui/server.test.ts
@@ -274,12 +274,16 @@ describe('server', () => {
               status: 'error',
               errors: [
                 {
-                  message: expect.stringContaining(
-                    "The following direct dependents of package 'a'",
-                  ) as string,
+                  message: [
+                    'a: has a major bump, but its direct dependents are not in the release spec: b',
+                    'Add them to the release spec, or set them to intentionally-skip.',
+                  ],
                 },
                 {
-                  message: '"nonexistent" is not a package in the project',
+                  message: [
+                    'nonexistent: is not a package in the project',
+                    'Check the name, or remove the line.',
+                  ],
                   lineNumber: 3,
                 },
               ],
@@ -291,6 +295,36 @@ describe('server', () => {
         expect(closeServer).not.toHaveBeenCalled();
       });
 
+      it('returns the problem and hint as the message', async () => {
+        const mode = buildMockMode({
+          plan: vi.fn().mockResolvedValue({
+            errors: [
+              { packageName: 'a', problem: 'is wrong', hint: 'Fix it.' },
+              { problem: 'is broken' },
+            ],
+          }),
+        });
+
+        await withApp(
+          {
+            context: buildContext(mode),
+            newReleaseVersion: '2.0.0',
+            closeServer: vi.fn(),
+          },
+          async (url) => {
+            const response = await postChoices(`${url}/api/release`, {});
+
+            expect(await response.json()).toStrictEqual({
+              status: 'error',
+              errors: [
+                { message: ['a: is wrong', 'Fix it.'] },
+                { message: 'is broken' },
+              ],
+            });
+          },
+        );
+      });
+
       it('applies, finishes, and closes the server', async () => {
         const plan = {
           releases: [{ name: 'a', newVersion: '1.1.0' }],
diff --git a/packages/create-release-branch/src/frontends/ui/server.ts b/packages/create-release-branch/src/frontends/ui/server.ts
index 591d440..1dabd99 100644
--- a/packages/create-release-branch/src/frontends/ui/server.ts
+++ b/packages/create-release-branch/src/frontends/ui/server.ts
@@ -193,10 +193,17 @@ export function createApp({
         if (!('plan' in result)) {
           res.json({
             status: 'error',
-            errors: result.errors.map(({ message, entryIndex }) =>
-              entryIndex === undefined
-                ? { message }
-                : { message, lineNumber: entryIndex + 2 },
+            errors: result.errors.map(
+              ({ packageName, entryIndex, problem, hint }) => {
+                const text =
+                  packageName === undefined
+                    ? problem
+                    : `${packageName}: ${problem}`;
+                const message = hint === undefined ? text : [text, hint];
+                return entryIndex === undefined
+                  ? { message }
+                  : { message, lineNumber: entryIndex + 2 };
+              },
             ),
           });
           return;