From 3be9b6486cbcdcf79ff034f5c10b43effef1d149 Mon Sep 17 00:00:00 2001
From: lilnasy <69170106+lilnasy@users.noreply.github.com>
Date: Mon, 8 Jan 2024 22:30:36 +0000
Subject: [PATCH 1/3] allow 404.html to be the catch-all route

---
 .../integrations/vercel/src/serverless/adapter.ts | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/packages/integrations/vercel/src/serverless/adapter.ts b/packages/integrations/vercel/src/serverless/adapter.ts
index dd07e723b644..db7f428051e1 100644
--- a/packages/integrations/vercel/src/serverless/adapter.ts
+++ b/packages/integrations/vercel/src/serverless/adapter.ts
@@ -287,9 +287,15 @@ You can set functionPerRoute: false to prevent surpassing the limit.`
 						excludeFiles,
 						maxDuration,
 					});
-					routeDefinitions.push({ src: '/.*', dest: 'render' });
+					for (const route of routes) {
+						if (route.prerender) continue
+						routeDefinitions.push({
+							src: route.pattern.source,
+							dest: 'render',
+						})
+					}
 				}
-
+				const fourOhFourRoute = routes.find((route) => route.pathname === '/404');
 				// Output configuration
 				// https://vercel.com/docs/build-output-api/v3#build-output-configuration
 				await writeJson(new URL(`./config.json`, _config.outDir), {
@@ -303,6 +309,11 @@ You can set functionPerRoute: false to prevent surpassing the limit.`
 						},
 						{ handle: 'filesystem' },
 						...routeDefinitions,
+						...fourOhFourRoute ? [{
+								src: '/.*',
+								dest: fourOhFourRoute.prerender ? '/404.html' : 'render',
+								status: 404,
+							}] : [],
 					],
 					...(imageService || imagesConfig
 						? {

From 13eab6d0b53e01734434a1d8bdd2efa8947b97bc Mon Sep 17 00:00:00 2001
From: lilnasy <69170106+lilnasy@users.noreply.github.com>
Date: Mon, 8 Jan 2024 23:06:35 +0000
Subject: [PATCH 2/3] add test

---
 .../prerendered-error-pages/astro.config.mjs  |  7 ++++++
 .../prerendered-error-pages/package.json      |  9 ++++++++
 .../src/pages/404.astro                       |  4 ++++
 .../src/pages/one.astro                       |  8 +++++++
 .../src/pages/two.astro                       |  8 +++++++
 .../test/prerendered-error-pages.test.js      | 23 +++++++++++++++++++
 .../integrations/vercel/test/static.test.js   |  2 +-
 pnpm-lock.yaml                                |  9 ++++++++
 8 files changed, 69 insertions(+), 1 deletion(-)
 create mode 100644 packages/integrations/vercel/test/fixtures/prerendered-error-pages/astro.config.mjs
 create mode 100644 packages/integrations/vercel/test/fixtures/prerendered-error-pages/package.json
 create mode 100644 packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/404.astro
 create mode 100644 packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/one.astro
 create mode 100644 packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/two.astro
 create mode 100644 packages/integrations/vercel/test/prerendered-error-pages.test.js

diff --git a/packages/integrations/vercel/test/fixtures/prerendered-error-pages/astro.config.mjs b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/astro.config.mjs
new file mode 100644
index 000000000000..b3f5bd362bae
--- /dev/null
+++ b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/astro.config.mjs
@@ -0,0 +1,7 @@
+import { defineConfig } from 'astro/config';
+import vercel from '@astrojs/vercel/serverless';
+
+export default defineConfig({
+	output: 'server',
+	adapter: vercel()
+});
diff --git a/packages/integrations/vercel/test/fixtures/prerendered-error-pages/package.json b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/package.json
new file mode 100644
index 000000000000..5cfc0e24c44d
--- /dev/null
+++ b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "@test/astro-vercel-prerendered-error-pages",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "@astrojs/vercel": "workspace:*",
+    "astro": "workspace:*"
+  }
+}
diff --git a/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/404.astro b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/404.astro
new file mode 100644
index 000000000000..162ff90b6820
--- /dev/null
+++ b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/404.astro
@@ -0,0 +1,4 @@
+---
+export const prerender = true
+---
+<h1>404</h1>
diff --git a/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/one.astro b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/one.astro
new file mode 100644
index 000000000000..0c7fb90a735e
--- /dev/null
+++ b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/one.astro
@@ -0,0 +1,8 @@
+<html>
+	<head>
+		<title>One</title>
+	</head>
+	<body>
+		<h1>One</h1>
+	</body>
+</html>
diff --git a/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/two.astro b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/two.astro
new file mode 100644
index 000000000000..e7ba9910e2a6
--- /dev/null
+++ b/packages/integrations/vercel/test/fixtures/prerendered-error-pages/src/pages/two.astro
@@ -0,0 +1,8 @@
+<html>
+	<head>
+		<title>Two</title>
+	</head>
+	<body>
+		<h1>Two</h1>
+	</body>
+</html>
diff --git a/packages/integrations/vercel/test/prerendered-error-pages.test.js b/packages/integrations/vercel/test/prerendered-error-pages.test.js
new file mode 100644
index 000000000000..9085662238d8
--- /dev/null
+++ b/packages/integrations/vercel/test/prerendered-error-pages.test.js
@@ -0,0 +1,23 @@
+import { loadFixture } from './test-utils.js';
+import { expect } from 'chai';
+
+describe('prerendered error pages routing', () => {
+	/** @type {import('./test-utils.js').Fixture} */
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/prerendered-error-pages/',
+		});
+		await fixture.build();
+	});
+
+	it('falls back to 404.html', async () => {
+		const deploymentConfig = JSON.parse(await fixture.readFile('../.vercel/output/config.json'));
+		expect(deploymentConfig.routes.at(-1)).to.deep.include({
+			src: '/.*',
+			dest: '/404.html',
+			status: 404,
+		});
+	});
+});
diff --git a/packages/integrations/vercel/test/static.test.js b/packages/integrations/vercel/test/static.test.js
index fc97e46ad7e9..a3d0ea738272 100644
--- a/packages/integrations/vercel/test/static.test.js
+++ b/packages/integrations/vercel/test/static.test.js
@@ -1,7 +1,7 @@
 import { loadFixture } from './test-utils.js';
 import { expect } from 'chai';
 
-describe('maxDuration', () => {
+describe('static routing', () => {
 	/** @type {import('./test-utils.js').Fixture} */
 	let fixture;
 
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 7dd02558ad6a..69b6abd703bf 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -4749,6 +4749,15 @@ importers:
         specifier: workspace:*
         version: link:../../../../../astro
 
+  packages/integrations/vercel/test/fixtures/prerendered-error-pages:
+    dependencies:
+      '@astrojs/vercel':
+        specifier: workspace:*
+        version: link:../../..
+      astro:
+        specifier: workspace:*
+        version: link:../../../../../astro
+
   packages/integrations/vercel/test/fixtures/redirects:
     dependencies:
       '@astrojs/vercel':

From 6a356c63f7b6a7f5ea654c02d51dadac37dfb938 Mon Sep 17 00:00:00 2001
From: lilnasy <69170106+lilnasy@users.noreply.github.com>
Date: Mon, 8 Jan 2024 22:36:03 +0000
Subject: [PATCH 3/3] add changeset

---
 .changeset/stale-pandas-count.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/stale-pandas-count.md

diff --git a/.changeset/stale-pandas-count.md b/.changeset/stale-pandas-count.md
new file mode 100644
index 000000000000..b67de833cf80
--- /dev/null
+++ b/.changeset/stale-pandas-count.md
@@ -0,0 +1,5 @@
+---
+"@astrojs/vercel": patch
+---
+
+Fixes an issue where the serverless function could not respond with a prerendered 404 page.