From e9f05bf8fb82bfe9e18ca4134d5a37bb471f844d Mon Sep 17 00:00:00 2001
From: "sentry[bot]" <39604003+sentry[bot]@users.noreply.github.com>
Date: Wed, 26 Aug 2026 22:42:44 +0000
Subject: [PATCH 1/2] fix(api-client): Use ApiClientError for non-JSON 400
 responses

---
 packages/mcp-core/src/api-client/client.ts | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/packages/mcp-core/src/api-client/client.ts b/packages/mcp-core/src/api-client/client.ts
index 3151c0dbe..a3ffb4e89 100644
--- a/packages/mcp-core/src/api-client/client.ts
+++ b/packages/mcp-core/src/api-client/client.ts
@@ -883,15 +883,21 @@ export class SentryApiService {
         responseText.includes("<html")
       ) {
         // HTML when expecting JSON usually indicates authentication or routing issues
-        throw new Error(
+        throw createApiError(
           `Expected JSON response but received HTML (${response.status} ${response.statusText}). This may indicate you're not authenticated, the URL is incorrect, or there's a server issue.`,
+          response.status,
+          undefined,
+          responseText,
         );
       }
 
       // Generic non-JSON error
-      throw new Error(
+      throw createApiError(
         `Expected JSON response but received ${contentType || "unknown content type"} ` +
           `(${response.status} ${response.statusText})`,
+        response.status,
+        undefined,
+        responseText,
       );
     }
 

From 27e4f15effed4b734e7df11a21ed88452f744c46 Mon Sep 17 00:00:00 2001
From: "sentry-junior[bot]"
 <264270552+sentry-junior[bot]@users.noreply.github.com>
Date: Wed, 23 Sep 2026 16:24:16 +0000
Subject: [PATCH 2/2] test(api-client): cover non-JSON validation errors

---
 .../mcp-core/src/api-client/client.test.ts    | 50 +++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/packages/mcp-core/src/api-client/client.test.ts b/packages/mcp-core/src/api-client/client.test.ts
index bd41cdbbe..868345e7b 100644
--- a/packages/mcp-core/src/api-client/client.test.ts
+++ b/packages/mcp-core/src/api-client/client.test.ts
@@ -3,6 +3,56 @@ import { http, HttpResponse } from "msw";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { ConfigurationError } from "../errors";
 import { SentryApiService } from "./client";
+import { ApiClientError, ApiValidationError } from "./errors";
+
+describe("validateEvents non-JSON responses", () => {
+  afterEach(() => mswServer.resetHandlers());
+
+  it.each(["text/plain", "text/html"])(
+    "classifies a 400 %s response as a client error",
+    async (contentType) => {
+      mswServer.use(
+        http.get(
+          "https://sentry.io/api/0/organizations/test-org/events/validate/",
+          () =>
+            new HttpResponse("Invalid query", {
+              status: 400,
+              headers: { "Content-Type": contentType },
+            }),
+        ),
+      );
+      const api = new SentryApiService({
+        host: "sentry.io",
+        accessToken: "test-token",
+      });
+      await expect(
+        api.validateEvents({ organizationSlug: "test-org" }),
+      ).rejects.toBeInstanceOf(ApiValidationError);
+    },
+  );
+
+  it("does not classify a successful HTML response as user input", async () => {
+    mswServer.use(
+      http.get(
+        "https://sentry.io/api/0/organizations/test-org/events/validate/",
+        () =>
+          new HttpResponse("<html>Unexpected response</html>", {
+            status: 200,
+            headers: { "Content-Type": "text/html" },
+          }),
+      ),
+    );
+    const api = new SentryApiService({
+      host: "sentry.io",
+      accessToken: "test-token",
+    });
+    const result = api.validateEvents({ organizationSlug: "test-org" });
+    await expect(result).rejects.toThrow(
+      "Expected JSON response but received HTML",
+    );
+    await expect(result).rejects.not.toBeInstanceOf(ApiClientError);
+  });
+});
 
 describe("getIssueUrl", () => {
   it("should work with sentry.io", () => {