4 files changed, 92 insertions, 2 deletions
diff --git a/.changeset/flat-baboons-nail.md b/.changeset/flat-baboons-nail.md
new file mode 100644
index 000000000..128d4234b
--- /dev/null
+++ b/.changeset/flat-baboons-nail.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Prevent frontmatter errors from crashing the dev server
diff --git a/packages/astro/src/content/types-generator.ts b/packages/astro/src/content/types-generator.ts
index e695f9e60..ab0e254ad 100644
--- a/packages/astro/src/content/types-generator.ts
+++ b/packages/astro/src/content/types-generator.ts
@@ -226,8 +226,17 @@ export async function createContentTypesGenerator({
 		events.push(event);
 
 		debounceTimeout && clearTimeout(debounceTimeout);
+		const runEventsSafe = async () => {
+			try {
+				await runEvents(opts);
+			} catch {
+				// Prevent frontmatter errors from crashing the server. The errors
+				// are still reported on page reflects as desired.
+				// Errors still crash dev from *starting*.
+			}
+		};
 		debounceTimeout = setTimeout(
-			async () => runEvents(opts),
+			runEventsSafe,
 			50 /* debounce to batch chokidar events */
 		);
 	}
diff --git a/packages/astro/test/units/content-collections/frontmatter.test.js b/packages/astro/test/units/content-collections/frontmatter.test.js
new file mode 100644
index 000000000..d4a9f1ece
--- /dev/null
+++ b/packages/astro/test/units/content-collections/frontmatter.test.js
@@ -0,0 +1,72 @@
+import { fileURLToPath } from 'node:url';
+import nodeFS from 'node:fs';
+import path from 'node:path';
+import slash from 'slash';
+
+import { runInContainer } from '../../../dist/core/dev/index.js';
+import { attachContentServerListeners } from '../../../dist/content/index.js';
+import { createFs, triggerFSEvent } from '../test-utils.js';
+
+const root = new URL('../../fixtures/alias/', import.meta.url);
+
+function getTypesDts() {
+	const typesdtsURL = new URL('../../../src/content/template/types.d.ts', import.meta.url);
+	const relpath = slash(path.relative(fileURLToPath(root), fileURLToPath(typesdtsURL)));
+	return {
+		[relpath]: nodeFS.readFileSync(typesdtsURL, 'utf-8')
+	};
+}
+
+describe('frontmatter', () => {
+	it('errors in content/ does not crash server', async () => {
+		const fs = createFs(
+			{
+				...getTypesDts(),
+				'/src/content/posts/blog.md': `
+					---
+					title: One
+					---
+				`,
+				'/src/content/config.ts': `
+					import { defineCollection, z } from 'astro:content';
+
+					const posts = defineCollection({
+						schema: z.string()
+					});
+
+					export const collections = {
+						posts
+					};
+				`,
+				'/src/pages/index.astro': `
+					---
+					---
+					<html>
+						<head><title>Test</title></head>
+						<body class="one">
+							<h1>Test</h1>
+						</body>
+					</html>
+				`,
+			},
+			root
+		);
+
+		await runInContainer({ fs, root }, async (container) => {
+			await attachContentServerListeners(container);
+
+			fs.writeFileFromRootSync(
+				'/src/content/posts/blog.md',
+				`
+				---
+				title: One
+				title: two
+				---
+				`
+			);
+			triggerFSEvent(container, fs, '/src/content/posts/blog.md', 'change');
+			await new Promise(resolve => setTimeout(resolve, 100));
+			// Note, if we got here, it didn't crash
+		});
+	})
+});
diff --git a/packages/astro/test/units/test-utils.js b/packages/astro/test/units/test-utils.js
index f142fceaf..68a86d475 100644
--- a/packages/astro/test/units/test-utils.js
+++ b/packages/astro/test/units/test-utils.js
@@ -3,7 +3,7 @@ import { Volume } from 'memfs';
 import httpMocks from 'node-mocks-http';
 import realFS from 'node:fs';
 import npath from 'path';
-import { fileURLToPath } from 'url';
+import { fileURLToPath, pathToFileURL } from 'url';
 import { unixify } from './correct-path.js';
 
 class VirtualVolume extends Volume {
@@ -26,6 +26,10 @@ class VirtualVolume extends Volume {
 		return npath.posix.join(this.#root, pth);
 	}
 
+	readFile(p, ...args) {
+		return super.readFile(this.#forcePath(p), ...args);
+	}
+
 	existsSync(p) {
 		return super.existsSync(this.#forcePath(p));
 	}