Fix 404 response leading to an infinite loop when there is no 404 page (#8136)

* fix: 404 response leads to infinite loop

* chore: changeset

---------

Co-authored-by: Nate Moore <natemoo-re@users.noreply.github.com>

2 files changed, 10 insertions, 1 deletions

diff --git a/.changeset/lemon-comics-jump.md b/.changeset/lemon-comics-jump.md
new file mode 100644
index 000000000..f2c9255f3
--- /dev/null
+++ b/.changeset/lemon-comics-jump.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix 404 response leading to an infinite loop when there is no 404 page.
diff --git a/packages/astro/src/vite-plugin-astro-server/route.ts b/packages/astro/src/vite-plugin-astro-server/route.ts
index f58d248a3..f387d07a4 100644
--- a/packages/astro/src/vite-plugin-astro-server/route.ts
+++ b/packages/astro/src/vite-plugin-astro-server/route.ts
@@ -259,7 +259,7 @@ export async function handleRoute({
 			await writeWebResponse(incomingResponse, response);
 		}
 	} else {
-		if (result.status === 404) {
+		if (result.status === 404 && has404Route(manifestData)) {
 			const fourOhFourRoute = await matchRoute('/404', env, manifestData);
 			return handleRoute({
 				...options,
@@ -380,3 +380,7 @@ function getStatus(matchedRoute?: MatchedRoute): 404 | 500 | undefined {
 	if (matchedRoute.route.route === '/404') return 404;
 	if (matchedRoute.route.route === '/500') return 500;
 }
+
+function has404Route(manifest: ManifestData): RouteData | undefined {
+	return manifest.routes.find((route) => route.route === '/404')
+}