From bfc8debf654dace272b8cc90b905a5581f8242a8 Mon Sep 17 00:00:00 2001
From: Vishal Sharma <tbhvishal@users.noreply.github.com>
Date: Tue, 10 Nov 2026 19:32:27 +0530
Subject: [PATCH 1/2] fix(utils): preserve trailing hash in ATX heading titles

---
 .../src/__tests__/markdownUtils.test.ts       | 42 +++++++++++++++++++
 .../docusaurus-utils/src/markdownUtils.ts     |  2 +-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts b/packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts
index 34648991ba35..e6ec8f9d7641 100644
--- a/packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts
+++ b/packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts
@@ -438,6 +438,48 @@ Lorem Ipsum
     });
   });
 
+  it('parses markdown h1 title preserving trailing hash in word (e.g. C#)', () => {
+    const markdown = dedent`
+
+          # Learn C#
+
+          Lorem Ipsum
+
+        `;
+    expect(parseMarkdownContentTitle(markdown)).toEqual({
+      content: markdown,
+      contentTitle: 'Learn C#',
+    });
+  });
+
+  it('parses markdown h1 title preserving trailing hash in word with closing #', () => {
+    const markdown = dedent`
+
+          # Learn C# #
+
+          Lorem Ipsum
+
+        `;
+    expect(parseMarkdownContentTitle(markdown)).toEqual({
+      content: markdown,
+      contentTitle: 'Learn C#',
+    });
+  });
+
+  it('parses markdown h1 title preserving trailing hash in word with anchor id', () => {
+    const markdown = dedent`
+
+          # Learn C# {#learn-csharp}
+
+          Lorem Ipsum
+
+        `;
+    expect(parseMarkdownContentTitle(markdown)).toEqual({
+      content: markdown,
+      contentTitle: 'Learn C#',
+    });
+  });
+
   it('parses markdown h1 title at the top followed by h2 title', () => {
     const markdown = dedent`
 
diff --git a/packages/docusaurus-utils/src/markdownUtils.ts b/packages/docusaurus-utils/src/markdownUtils.ts
index 3a82a52cbb6e..d2b519265cd2 100644
--- a/packages/docusaurus-utils/src/markdownUtils.ts
+++ b/packages/docusaurus-utils/src/markdownUtils.ts
@@ -334,7 +334,7 @@ export function parseMarkdownContentTitle(
       contentTitle: toTextContentTitle(
         regularTitleMatch
           .groups!.title!.trim()
-          .replace(/\s*(?:\{#*[\w-]+\}|#+)$/, ''),
+          .replace(/(?:\s*\{#*[\w-]+\}|\s+#+)$/, ''),
       ).trim(),
     };
   }

From 1ec580fd9614dd723af3365c42d62f02c844728c Mon Sep 17 00:00:00 2001
From: Vishal Sharma <tbhvishal@users.noreply.github.com>
Date: Tue, 10 Nov 2026 19:51:33 +0530
Subject: [PATCH 2/2] fix(utils): handle headings consisting only of closing
 hashes

---
 .../src/__tests__/markdownUtils.test.ts            | 14 ++++++++++++++
 packages/docusaurus-utils/src/markdownUtils.ts     |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts b/packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts
index e6ec8f9d7641..fef512de0e97 100644
--- a/packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts
+++ b/packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts
@@ -480,6 +480,20 @@ Lorem Ipsum
     });
   });
 
+  it('parses markdown h1 title consisting only of closing hashes as empty', () => {
+    const markdown = dedent`
+
+          # ###
+
+          Lorem Ipsum
+
+        `;
+    expect(parseMarkdownContentTitle(markdown)).toEqual({
+      content: markdown,
+      contentTitle: '',
+    });
+  });
+
   it('parses markdown h1 title at the top followed by h2 title', () => {
     const markdown = dedent`
 
diff --git a/packages/docusaurus-utils/src/markdownUtils.ts b/packages/docusaurus-utils/src/markdownUtils.ts
index d2b519265cd2..022079f5d757 100644
--- a/packages/docusaurus-utils/src/markdownUtils.ts
+++ b/packages/docusaurus-utils/src/markdownUtils.ts
@@ -334,7 +334,7 @@ export function parseMarkdownContentTitle(
       contentTitle: toTextContentTitle(
         regularTitleMatch
           .groups!.title!.trim()
-          .replace(/(?:\s*\{#*[\w-]+\}|\s+#+)$/, ''),
+          .replace(/(?:\s*\{#*[\w-]+\}|\s+#+|^#+)$/, ''),
       ).trim(),
     };
   }