Astro reports “Adapter does not support server output” when the adapter in your config can only produce a static site, but the project contains pages that render on demand. The full message names the adapter: it “is configured to output a static website, but the project contains server-rendered pages.” Either switch to an adapter that can run a server, or make those pages prerendered.
Key Takeaways
- Some adapters and integrations only support static output.
- Any
prerender = falseroute, oroutput: 'server', conflicts with them.- Official adapters for Node, Cloudflare, Netlify and Vercel all support on-demand pages.
- If you didn’t mean to have server pages, find and remove the opt-out.
Find the server-rendered routes
grep -rn "prerender = false" src/
grep -n "output" astro.config.mjsRemember that endpoints (src/pages/**/*.ts) count, and so do pages using features that require a server, such as actions submitted from a form.
Fix 1: use an adapter that supports a server
Replace the static-only adapter with the official one for your host:
npx astro add netlify # or node, cloudflare, vercelThen remove the old adapter import from astro.config.mjs so only one adapter remains. Check your host’s docs if you were using a community adapter: some exist specifically to add static hosting features and were never meant to run code.
Fix 2: prerender everything
If the on-demand pages don’t need request data, remove the opt-out:
- export const prerender = false;and, if you set it, remove output: 'server'. Dynamic routes then need getStaticPaths(); see getStaticPaths() required.
Which approach to choose
| Situation | Choose |
|---|---|
| Pages need cookies, auth or live data | Fix 1 |
| Only a form needs a server | A third-party form endpoint, then Fix 2 |
| Pages were marked on-demand by habit | Fix 2 |
| Host only serves static files (GitHub Pages, S3) | Fix 2, or move hosts |
GitHub Pages and plain object storage can’t run server code at all, so no adapter will help there. The Astro deploy guide compares hosts that can.
Related: Cannot use server-side rendering without an adapter is the version of this error with no adapter at all. The Astro SSR guide covers output modes, and the on-demand rendering docs list adapter features.
FAQ
Can I have two adapters in one Astro project?
No. Astro accepts a single adapter. Pick the one for your production host.
Why did this start after upgrading Astro?
Older releases had an output: 'hybrid' mode. Since Astro 5, use output: 'static' with prerender = false on individual pages, and make sure your adapter version supports the Astro version you upgraded to.