Astro Server Islands and Vercel ISR causes 404

Help
1

Hello,

does Vercel support Astro Server Island components together with ISR?

I did a simple test in blank Astro project, I added Server Island component and it worked only when ISR was not enabled. If I enabled ISR, the index page loads but call to _server-island/component_name returns HTTP/404.

This was the only difference between the two builds.

    isr: {

       bypassToken: "***",
       exclude: [ "/some/path1", ...],

    }

# packages.json 
# Tested with Astro 5.0.5 and astro@latest (5.1.1)

  "dependencies": {
    "@astrojs/vercel": "^8.0.1",
    "astro": "^5.0.5"
  }

# astro.config.mjs

import vercel from '@astrojs/vercel';

export default defineConfig({
  output: "server",
  adapter: vercel({
    isr: {
       bypassToken: "***",
       exclude: [ "/some/path1", ],
    },
  }),
});

The index page is just simple call of Server Island component using server:defer.

# index.astro
---
export const prerender = false;
import TimeComponent from '../components/time.astro';
---

<html lang="en">
	<head>
		<meta charset="utf-8" />
		<title>Astro</title>
	</head>
	<body>
        <p>Timestamp: <TimeComponent server:defer /></p>
	</body>
</html>

The component itself just returns a timestamp.

# time.astro
---
const timestamp = Date.now();
---

{ timestamp }
2

There’s another community post with 404 debugging tips that might be helpful. Please give these solutions a try and let us know how it goes.

A human should be around soon to offer more advice. But you can also get helpful information quickly by asking v0.

3

Thx bot, not helpful at all as bug report is of completely different nature.

4

Upgraded Astro to 5.1.2 but Server Islands still don’t work returning 404.