[Bug?]: Vite 8 rejects UnoCSS virtual CSS request in SolidStart dev SSR

[Jel1ySpot]

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Current behavior 😯

When using UnoCSS with SolidStart v2 and Vite 8, the development SSR manifest requests UnoCSS's virtual stylesheet with an ?inline query: /__uno.css?inline

Server log:

Error: Denied ID /__uno.css?inline
    at loadAndTransform (file:///./node_modules/.pnpm/vite@8.1.4/node_modules/vite/dist/node/chunks/node.js:20042:31)
...
at async listenerForInvokeHandler (file:///./node_modules/.pnpm/vite@8.1.4/node_modules/vite/dist/node/chunks/node.js:26284:13) {
    code: 'ERR_DENIED_ID',
    id: '/__uno.css?inline',
    runnerError: Error: RunnerError
        at reviveInvokeError (file:///./node_modules/.pnpm/vite@8.1.4/node_modules/vite/dist/node/module-runner.js:547:64)
        at Object.invoke (file:///./node_modules/.pnpm/vite@8.1.4/node_modules/vite/dist/node/module-runner.js:620:11)
        at ModuleRunner.getModuleInformation (file:///./node_modules/.pnpm/vite@8.1.4/node_modules/vite/dist/node/module-runner.js:1199:7)
        at request (file:///./node_modules/.pnpm/vite@8.1.4/node_modules/vite/dist/node/module-runner.js:1216:83)
        at ./node_modules/.pnpm/@solidjs+start@2.0.0_@solid_1d017123e3fcfa0bc1667ffc27bdb253/node_modules/@solidjs/start/dist/server/manifest/dev-ssr-manifest.js:18:27
        at async Promise.all (index 0)
        at Object.getAssets (./node_modules/.pnpm/@solidjs+start@2.0.0_@solid_1d017123e3fcfa0bc1667ffc27bdb253/node_modules/@solidjs/start/dist/server/manifest/dev-ssr-manifest.js:16:20)
        at createPageEvent (./node_modules/.pnpm/@solidjs+start@2.0.0_@solid_1d017123e3fcfa0bc1667ffc27bdb253/node_modules/@solidjs/start/dist/server/handler.js:115:13)
        at ./node_modules/.pnpm/@solidjs+start@2.0.0_@solid_1d017123e3fcfa0bc1667ffc27bdb253/node_modules/@solidjs/start/dist/server/handler.js:45:29
        at Module.fetch (file:///./node_modules/nitro/dist/runtime/internal/vite/dev-worker.mjs:154:12)
  },
  status: 500,
  statusText: undefined,
  headers: undefined,
  data: undefined,
  body: undefined,
  unhandled: true
}
...

Expected behavior 🤔

SolidStart should starts successfully without error, with either:

1. resolve /__uno.css?inline as a virtual module before Vite performs filesystem ID validation; or
2. provide a documented integration path for UnoCSS virtual CSS modules in development SSR.

Steps to reproduce 🕹

Steps: Create a SolidStart v2 project using with-unocss tempalate.

1. pnpm create solid
2. Choose SolidStart + v2
3. Choose with-unocss
4. cd project-name && pnpm installl && pnpm dev

Context 🔦

No response

Your environment 🌎

System:
  OS: Windows 11 Perfessional Edition 25H2 26200.8973
Binaries:
  Node.js: 24.0.1
npmPackage:
  `@solidjs/start`: 2.0.0
Package manager:
  pnpm 10.29.3

[birkskyum]

Tracked upstream in unocss/unocss#5271 with a reproduction using the official SolidStart with-unocss template.

The failure is confirmed with the current releases, unocss@66.7.5 and vite@8.2.1. The UnoCSS entry appears in the SSR module graph as:

{
  id: "/__uno.css",
  url: "/__uno.css",
  file: "/__uno.css"
}

Because file is not null, the condition introduced by #2293 does not run, and its published preview package still returns the same HTTP 500 with ERR_DENIED_ID /__uno.css?inline.

A control virtual CSS plugin using the standard Vite \0-prefixed resolved ID works with unchanged SolidStart 2.0.0. This therefore appears to be an upstream UnoCSS virtual-module/?inline compatibility issue.

unocss/unocss#4884 remains related, but it covers a Vite 7 production-build failure rather than this Vite 8 development SSR failure.

[birkskyum]

Fixed upstream