diff --git a/.eslintignore b/.eslintignore
index 9b59cd01a..59bf495f4 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -1537,6 +1537,7 @@ packages/tools/update-readme-download.test.js
 packages/tools/update-readme-download.js
 packages/tools/update-readme-sponsors.js
 packages/tools/updateMarkdownDoc.js
+packages/tools/utils/discourse.test.js
 packages/tools/utils/discourse.js
 packages/tools/utils/loadSponsors.js
 packages/tools/utils/translation.js
diff --git a/.gitignore b/.gitignore
index a6bc8fa78..6b4607e10 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1514,6 +1514,7 @@ packages/tools/update-readme-download.test.js
 packages/tools/update-readme-download.js
 packages/tools/update-readme-sponsors.js
 packages/tools/updateMarkdownDoc.js
+packages/tools/utils/discourse.test.js
 packages/tools/utils/discourse.js
 packages/tools/utils/loadSponsors.js
 packages/tools/utils/translation.js
diff --git a/packages/tools/postPreReleasesToForum.ts b/packages/tools/postPreReleasesToForum.ts
index 428b69783..d6f070bd9 100644
--- a/packages/tools/postPreReleasesToForum.ts
+++ b/packages/tools/postPreReleasesToForum.ts
@@ -1,7 +1,7 @@
 import { pathExists } from 'fs-extra';
 import { readFile, writeFile } from 'fs/promises';
 import { GitHubRelease, gitHubLatestReleases, gitHubLinkify } from './tool-utils';
-import { config, createPost, createTopic, getForumTopPostByExternalId, getTopicByExternalId, updatePost } from './utils/discourse';
+import { config, createPost, createTopic, getForumTopPostByExternalId, getTopicByExternalId, trimPostToMaximumLength, updatePost } from './utils/discourse';
 import { compareVersions } from 'compare-versions';
 import dayjs = require('dayjs');
 import { getRootDir } from '@joplin/utils';
@@ -135,7 +135,11 @@ const processReleases = async (releases: GitHubRelease[], platform: Platform, st
 
 				await updatePost(topPost.id, {
 					title: topicTitle,
-					raw: `${topPost.raw}\n\n${postBody}`,
+					// With a large number of pre-releases, the top post can get very long
+					// and needs to be trimmed.
+					raw: trimPostToMaximumLength(
+						`${topPost.raw}\n\n${postBody}`,
+					),
 					edit_reason: 'Auto-updated by script',
 				});
 
diff --git a/packages/tools/utils/discourse.test.ts b/packages/tools/utils/discourse.test.ts
new file mode 100644
index 000000000..af53ed7d3
--- /dev/null
+++ b/packages/tools/utils/discourse.test.ts
@@ -0,0 +1,18 @@
+import { trimPostToMaximumLength } from './discourse';
+
+describe('utils/discourse', () => {
+	it('trimPostToMaximumLength should allow trimming posts to a maximum length', () => {
+		const makeLongString = (length: number) => {
+			const resultParts = [];
+			while (resultParts.length < length) {
+				resultParts.push('1');
+			}
+			return resultParts.join('');
+		};
+
+		const longContent = makeLongString(70_000);
+		const trimmed = trimPostToMaximumLength(longContent);
+		expect(trimmed.length).toBeLessThan(65_000);
+		expect(trimmed).toContain(`${longContent.substring(0, 65_000 - 153)}...\n\n**Note**:`);
+	});
+});
diff --git a/packages/tools/utils/discourse.ts b/packages/tools/utils/discourse.ts
index dbc88e0e8..730b00b76 100644
--- a/packages/tools/utils/discourse.ts
+++ b/packages/tools/utils/discourse.ts
@@ -1,3 +1,4 @@
+import { substrWithEllipsis } from '@joplin/lib/string-utils';
 import { msleep } from '@joplin/utils/time';
 import fetch from 'node-fetch';
 
@@ -141,3 +142,16 @@ export const createPost = async (topicId: number, post: any): Promise<ForumTopic
 export const updatePost = async (postId: number, content: any): Promise<void> => {
 	await execApi(HttpMethod.PUT, `posts/${postId}.json`, content);
 };
+
+export const trimPostToMaximumLength = (postBody: string) => {
+	// Discourse has a maximum post length of 65_000:
+	const maximumLength = 65_000;
+	if (postBody.length > maximumLength) {
+		return [
+			substrWithEllipsis(postBody, 0, maximumLength - 150),
+			'**Note**: The full content of this post is longer than permitted by Discourse.',
+		].join('\n\n');
+	}
+
+	return postBody;
+};