Fix server island build error by matthewp · Pull Request #15888 · withastro/astro

matthewp · 2026-03-12T17:52:32Z

Changes

Fix server island manifest placeholder replacement when generated chunks use double-quoted string literals.
Use quote-agnostic matching for detection and replacement in server-island build hooks.
Fixes [v6 / Cloudflare] serverIslandMap?.get is not a function in pre-rendered page #15886

Testing

Add a regression unit test that simulates quote-style conversion and asserts the output contains materialized serverIslandMap/serverIslandNameMap maps.

Docs

No docs update needed; this is a bug fix for incorrect runtime behavior.

Rollup can emit server-island placeholders with either single or double quotes, which caused map injection to be skipped in some adapter builds. Match placeholders quote-agnostically and add a regression test that verifies the maps are materialized in output.

changeset-bot · 2026-03-12T17:52:44Z

🦋 Changeset detected

Latest commit: ce7e29a

The changes in this PR will be included in the next version bump.

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

codspeed-hq · 2026-03-12T18:09:20Z

Merging this PR will not alter performance

✅ 18 untouched benchmarks

_{Comparing server-island-name (ce7e29a) with main (759f946)}

pkg-pr-new · 2026-03-12T18:36:05Z

astro

npm i https://pkg.pr.new/astro@15888

create-astro

npm i https://pkg.pr.new/create-astro@15888

@astrojs/cloudflare

npm i https://pkg.pr.new/@astrojs/cloudflare@15888

@astrojs/preact

npm i https://pkg.pr.new/@astrojs/preact@15888

@astrojs/check

npm i https://pkg.pr.new/@astrojs/check@15888

@astrojs/language-server

npm i https://pkg.pr.new/@astrojs/language-server@15888

astro-vscode

npm i https://pkg.pr.new/astro-vscode@15888

commit: 2cb31aa

ematipico · 2026-03-12T18:45:37Z

packages/astro/src/core/server-islands/vite-plugin-server-islands.ts

 const RESOLVED_SERVER_ISLAND_MANIFEST = '\0' + SERVER_ISLAND_MANIFEST;

-export const serverIslandPlaceholderMap = "'$$server-islands-map$$'";
+const serverIslandPlaceholderMap = "'$$server-islands-map$$'";


If you're looking for a solution that is vite 8 friendly, use template literals.

Turns out that oxc/rolldown do a bunch of normalisation with strings, and sometimes it transforms them

Oh wait, that doesn't matter here, this code isn't loaded by Vite.

It actually does... 😅

I had to apply this change 1cae171

It's just a FYI, no need to change it here. I wanted to let you know

CaiJimmy · 2026-03-12T18:46:17Z

Thanks for the quick fix!

I have encountered now with a different error in preview environment (using the same reproducible example, but with astro package given by pkg-pr-new):

GET / 200 OK (5ms)
GET /.well-known/appspecific/com.chrome.devtools.json 404 Not Found (3ms)
19:43:32 [ERROR] Error: No such module "dist/server/chunks/Island_!~{00b}~.mjs".
    at file:///Users/jimmy/Documents/repro-cf-v6/dist/server/chunks/_virtual_astro_server-island-manifest_zfG9aQW0.mjs:4:19
    at page (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:9222:35)
    at async callComponentAsTemplateResultOrResponse (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:7116:25)
    at async renderToReadableStream (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:7064:26)
    at async renderPage (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:8320:14)
    at async lastNext (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:11522:25)
    at async callMiddleware (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:8412:10)
    at async RenderContext.render (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:11556:73)
    at async App.render (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:12451:20)
    at async Object.handle [as fetch] (file:///Users/jimmy/Documents/repro-cf-v6/dist/server/entry.mjs:12961:20)
GET /_server-islands/Island 500 Internal Server Error (4ms)

It's trying to import a non-existent file from chunks folder. The dev server does not work neither. Not sure if this is related. Should I create a separate issue?

matthewp · 2026-03-12T18:50:57Z

@CaiJimmy no, will keep this one.

CaiJimmy · 2026-03-12T18:52:45Z

Thanks!

I just tested with the current stable version of Astro 6 and can confirm that it does not generate the dist/server/chunks/Island_!~{00b}~.mjs file neither.

matthewp · 2026-03-12T19:36:16Z

@CaiJimmy can you try with:

npm i https://pkg.pr.new/astro@fbf9d83

CaiJimmy · 2026-03-12T19:47:25Z

@matthewp I can confirm that now preview environment working correctly with server:defer, generating the correct chunk file.

But dev server still gives error with prerenderEnvironment: 'node'. I can see in the console that it's a 400 error, but no error log is given currently so I'm afraid that I cannot provide any more useful information to you:

➜  repro-cf-v6 git:(main) ✗ pnpm dev

> repro-cf-v6@0.0.1 dev /Users/jimmy/Documents/repro-cf-v6
> astro dev

20:45:46 [@astrojs/cloudflare] Enabling image processing with Cloudflare Images for production with the "IMAGES" Images binding.
20:45:46 [@astrojs/cloudflare] Enabling sessions with Cloudflare KV with the "SESSION" KV binding.
[vite] connected.
20:45:47 [types] Generated 0ms
20:45:47 [WARN] [content] Content config not loaded
 astro  v6.0.4 ready in 1155 ms
┃ Local    http://localhost:4321/
┃ Network  use --host to expose
20:45:47 watching for file changes...
20:45:48 [200] / 17ms
20:45:48 [200] / 20ms
20:45:48 [vite] 20:45:48 [404] /@id/astro/runtime/client/dev-toolbar/astro_runtime_client_dev-toolbar_entrypoint__js.js.map 9ms
20:45:48 [vite] 20:45:48 [400] /_server-islands/Island 12ms

Is there any way to expose more error stack information here?

CaiJimmy · 2026-03-12T19:50:01Z

With prerenderEnvironment: 'workerd', server island in dev server seems to be working correctly.

matthewp · 2026-03-12T19:53:04Z

@CaiJimmy I think I know the dev issue here. It's unrelated to this change so I'll look into that as a separate PR.

matthewp · 2026-03-12T20:17:53Z

@CaiJimmy #15891

CaiJimmy · 2026-03-12T20:30:32Z

Thank you!

I'm currently testing this new version on my website, and found that there is some issue with importing third party libraries (using the top level import, not require)

The example server island would be something like this:

---
import { encodeBase64 } from "@oslojs/encoding";
 
const data: Uint8Array = new TextEncoder().encode("hello world");
const encoded = encodeBase64(data);
---

<p>Encoded: {encoded}</p>

The resulting file after running build keeps import { encodeBase64 } from "@oslojs/encoding";, and results error in preview (and I guess also in the real cloudflare worker environment):

Inside ./transition_BPFN3ezl.mjs, there is another direct import from the library:

import { decodeBase64, encodeBase64, decodeHex, encodeHexUpperCase } from '@oslojs/encoding';

Error when running preview:

➜  repro-cf-v6 git:(main) pnpm preview

> repro-cf-v6@0.0.1 preview /Users/jimmy/Documents/repro-cf-v6
> astro preview

21:27:44 [@astrojs/cloudflare] Enabling image processing with Cloudflare Images for production with the "IMAGES" Images binding.
21:27:44 [@astrojs/cloudflare] Enabling sessions with Cloudflare KV with the "SESSION" KV binding.
21:27:44 [@astrojs/cloudflare]
 astro  v13.1.1 ready in 29 ms

┃ Local    http://localhost:4321/

GET / 200 OK (14ms)
21:27:46 [ERROR] Error: No such module "dist/server/chunks/@oslojs/encoding".
  imported from "dist/server/chunks/Island_CZSxsmqZ.mjs"
GET /_server-islands/Island 500 Internal Server Error (17ms)
21:27:46 [ERROR] Error: No such module "dist/server/chunks/@oslojs/encoding".
  imported from "dist/server/chunks/Island_CZSxsmqZ.mjs"
GET /_server-islands/Island 500 Internal Server Error (2ms)

I believe (?) this is not related with https://docs.astro.build/en/guides/integrations-guide/cloudflare/#some-dependencies-might-need-to-be-pre-compiled, because it's using the ES6 export and import syntax.

I have updated the repo with a minimal reproducible example: https://github.com/CaiJimmy/astro-v6-prerender

Should I create a separate issue for this? Seems like a bundle problem.

matthewp · 2026-03-12T22:09:29Z

@CaiJimmy No, I think that might be related to this fix. I'll try and get another test for this scenario and it fixed here.

matthewp · 2026-03-13T16:23:42Z

@CaiJimmy here's new ones for you to try:

npm i https://pkg.pr.new/astro@a68cdfa
npm i https://pkg.pr.new/@astrojs/cloudflare@a68cdfa

CaiJimmy · 2026-03-13T16:30:38Z

Thanks!

With prerenderEnvironment set to workerd, third party libraries are correctly bundled:

/// island_CllqxkrA.mjs
globalThis.process ??= {};
globalThis.process.env ??= {};
import { A as AstroError, ao as InvalidComponentArgs, ap as encodeBase64, l as maybeRenderHead, D as renderTemplate } from "./transition_BffVS1kO.mjs";

However, when it's set to node, it will no longer bundle:

/// island_C0XpBDl0.mjs
globalThis.process ??= {}; globalThis.process.env ??= {};
import { A as AstroError, ao as InvalidComponentArgs, l as maybeRenderHead, D as renderTemplate } from './transition_BPFN3ezl.mjs';
import { encodeBase64 } from '@oslojs/encoding';

The test was done using this example: https://github.com/CaiJimmy/astro-v6-prerender

matthewp · 2026-03-13T16:38:51Z

@CaiJimmy What is incorrect about the second example there? @oslo/encoding is not bundled because dependencies are not bundled by default in Node.js. Does this cause a problem?

CaiJimmy · 2026-03-13T16:42:05Z

@CaiJimmy What is incorrect about the second example there? @oslo/encoding is not bundled because dependencies are not bundled by default in Node.js. Does this cause a problem?

Yes, because this dependency is used by the Server Island script, which will be executed in the Worker environment.

It wouldn't be a problem if the pre-render page itself used it because it would be executed in a normal Node environment.

matthewp · 2026-03-13T16:58:10Z

Right ok, that's interesting. You are hitting the hardest part of this refactor 😅. I've been trying to avoid flipping the order that the environments run, but I might need to do that. Let me try it out.

matthewp · 2026-03-13T18:28:59Z

@CaiJimmy can you try this one?

npm i https://pkg.pr.new/@astrojs/cloudflare@2cb31aa
npm i https://pkg.pr.new/astro@2cb31aa

CaiJimmy · 2026-03-13T20:54:39Z

Thanks!

I have tested it, and it is now compiling and bundling the dependencies correctly.

I have also tested this version on my website and found that Server Island requests are returning empty responses in preview server. I need some time to create a minimal reproducible example, but I think it's probably related to the combination of Server Island and the front-end framework hydration (I'm using Solid.js), because plain text inside Server Island is returned in the response correctly.

Thanks again for the fix!

Edit: here is the minimal reproducible example: https://github.com/CaiJimmy/astro-v6-prerender/blob/main/src/pages/island.astro

Solid.js component (I haven't tested yet other frameworks) inside a Astro Server Island component is not rendered:

---
import A from "./A";
---

<A content={'test'} />

export default function A({ content }: { content?: string }) {
    return (
        <div>
            <p>Content: {content}</p>
        </div>
    );
}

Empty response is returned by the server (it's a 200 response, no error in console):

Edit2: I have tested with React, and it has the same issue.
Edit3: This issue is present in both node and workerd prerender environment

Server islands used only on prerendered pages produce broken chunk filenames. Patch swaps build order (prerender first, then SSR) and uses quote-agnostic placeholder matching. Tracks: withastro/astro#15888 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

soklovsk · 2026-03-16T09:22:47Z

Fixes 15903.

matthewp · 2026-03-16T12:55:31Z

@CaiJimmy I think I'm going to release this as I'm confident it fixes most of the server island issues people are facing. Once that's out if you could file a new issue about nested client island inside I'll get that resolved separately.

github-actions bot added the pkg: astro Related to the core `astro` package (scope) label Mar 12, 2026

matthewp changed the title ~~fix(astro): make server-island placeholder replacement quote-agnostic~~ Fix server island build error Mar 12, 2026

fix(astro): address lint in server-islands placeholder matching

a2225f8

matthewp added the pr preview Apply this label to a PR to generate a preview release label Mar 12, 2026

matthewp marked this pull request as ready for review March 12, 2026 18:35

github-actions bot removed the pr preview Apply this label to a PR to generate a preview release label Mar 12, 2026

ematipico approved these changes Mar 12, 2026

View reviewed changes

matthewp marked this pull request as draft March 12, 2026 18:51

fix(astro): resolve server-island chunk imports in prerender builds

d50877d

matthewp added the pr preview Apply this label to a PR to generate a preview release label Mar 12, 2026

github-actions bot removed the pr preview Apply this label to a PR to generate a preview release label Mar 12, 2026

matthewp marked this pull request as ready for review March 12, 2026 20:02

fix(cloudflare): bundle prerender server-island dependencies

e0e64e3

github-actions bot added the pkg: integration Related to any renderer integration (scope) label Mar 13, 2026

matthewp added 2 commits March 13, 2026 11:28

chore(changeset): add cloudflare patch note for server islands

ce0e7e8

chore(changeset): use standard present-tense wording

558e268

matthewp mentioned this pull request Mar 13, 2026

Server Islands causing build error "Could not find server component name" #15903

Closed

1 task

matthewp added the pr preview Apply this label to a PR to generate a preview release label Mar 13, 2026

github-actions bot removed the pr preview Apply this label to a PR to generate a preview release label Mar 13, 2026

matthewp added 2 commits March 13, 2026 13:45

fix(astro): build server islands in SSR environment

c74ff11

fix(astro): emit server-island chunks before render phase

a68a287

matthewp added the pr preview Apply this label to a PR to generate a preview release label Mar 13, 2026

github-actions bot removed the pr preview Apply this label to a PR to generate a preview release label Mar 13, 2026

fix(astro): resolve prerender-discovered islands on Windows

ce7e29a

trueberryless mentioned this pull request Mar 16, 2026

feat: add support for Astro 6 trueberryless-org/starlight-latest-version#68

Open

matthewp merged commit 925252e into main Mar 16, 2026
26 checks passed

matthewp deleted the server-island-name branch March 16, 2026 12:55

astrobot-houston mentioned this pull request Mar 16, 2026

[ci] release #15889

Merged

Uh oh!

Conversation

matthewp commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Changes

Testing

Docs

Uh oh!

changeset-bot bot commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🦋 Changeset detected

Uh oh!

codspeed-hq bot commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Merging this PR will not alter performance

Uh oh!

pkg-pr-new bot commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

ematipico Mar 12, 2026

Choose a reason for hiding this comment

Uh oh!

matthewp Mar 12, 2026

Choose a reason for hiding this comment

Uh oh!

matthewp Mar 12, 2026

Choose a reason for hiding this comment

Uh oh!

ematipico Mar 13, 2026

Choose a reason for hiding this comment

Uh oh!

CaiJimmy commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

matthewp commented Mar 12, 2026

Uh oh!

CaiJimmy commented Mar 12, 2026

Uh oh!

matthewp commented Mar 12, 2026

Uh oh!

CaiJimmy commented Mar 12, 2026

Uh oh!

CaiJimmy commented Mar 12, 2026

Uh oh!

matthewp commented Mar 12, 2026

Uh oh!

matthewp commented Mar 12, 2026

Uh oh!

CaiJimmy commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

matthewp commented Mar 12, 2026

Uh oh!

matthewp commented Mar 13, 2026

Uh oh!

CaiJimmy commented Mar 13, 2026

Uh oh!

matthewp commented Mar 13, 2026

Uh oh!

CaiJimmy commented Mar 13, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

matthewp commented Mar 13, 2026

Uh oh!

matthewp commented Mar 13, 2026

Uh oh!

CaiJimmy commented Mar 13, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

soklovsk commented Mar 16, 2026

Uh oh!

matthewp commented Mar 16, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

matthewp commented Mar 12, 2026 •

edited

Loading

changeset-bot bot commented Mar 12, 2026 •

edited

Loading

codspeed-hq bot commented Mar 12, 2026 •

edited

Loading

pkg-pr-new bot commented Mar 12, 2026 •

edited

Loading

CaiJimmy commented Mar 12, 2026 •

edited

Loading

CaiJimmy commented Mar 12, 2026 •

edited

Loading

CaiJimmy commented Mar 13, 2026 •

edited

Loading

CaiJimmy commented Mar 13, 2026 •

edited

Loading