Unknown file extension ".css" for ...

[13RTK]

Describe:
Looks like same issue with #19946 , but occur in v4.2.4, more info in daisyUI

Reproduction:
https://stackblitz.com/~/github.com/13RTK/reproduct

Source code:
https://github.com/13RTK/reproduct

What version of Tailwind CSS are you using?

For example: v4.2.4

What build tool (or framework if it abstracts the build tool) are you using?

Vite 8.0.9

What version of Node.js are you using?

v24.15.0

What browser are you using?

All browsers

What operating system are you using?

For example: macOS, Windows

Reproduction URL

A Tailwind Play link or public GitHub repo that includes a minimal reproduction of the bug. Please do not link to your actual project, what we need instead is a minimal reproduction in a fresh project without any unnecessary code. This means it doesn't matter if your real project is private/confidential, since we want a link to a separate, isolated reproduction anyways.

A reproduction is required when filing an issue — any issue opened without a reproduction will be closed and you'll be asked to create a new issue that includes a reproduction. We're a small team and we can't keep up with the volume of issues we receive if we need to reproduce each issue from scratch ourselves.

Describe your issue

Describe the problem you're seeing, any important steps to reproduce and what behavior you expect instead.

[dBaliukynas]

Same. I'm also using daisyUI and getting this. Started happening since 4.2.3. It worked well on 4.2.2

[jonjes]

I'm also seeing this bug when trying to use Tailwind with DaisyUI on Sveltekit. To verify, I created a new app and followed the DaisyUI Svelte installation instructions exactly. I see the error message

[vite] Internal server error: Unknown file extension ".css" for [project_path]/node_modules/.pnpm/daisyui@5.5.19/node_modules/daisyui/daisyui.css

 Plugin: @tailwindcss/vite:generate:serve
  File: [project_path]/src/app.css
      at Object.getFileProtocolModuleFormat [as file:] (node:internal/modules/esm/get_format:183:9)
      at defaultGetFormat (node:internal/modules/esm/get_format:209:36)
      at defaultLoad (node:internal/modules/esm/load:119:22)
      at async nextLoad (node:internal/modules/esm/hooks:748:22)
      at async Hooks.load (node:internal/modules/esm/hooks:385:20)
      at async MessagePort.handleMessage (node:internal/modules/esm/worker:199:18)

[cernyjakub]

I am seeing this with 4.2.4 too..

[RobinMalfait]

Hey all! This should be fixed by #19949 but before we release a new version, can any of you verify if it's solved for your use case?

You can test with the insiders version that contains this fix:

npm install @tailwindcss/vite@0.0.0-insiders.f3fdda2

Let me know if you run into any issues!

[dBaliukynas]

I can confirm that @tailwindcss/vite@0.0.0-insiders.f3fdda2 works well for me.

[13RTK]

Hey all! This should be fixed by #19949 but before we release a new version, can any of you verify if it's solved for your use case?

You can test with the insiders version that contains this fix:

npm install @tailwindcss/vite@0.0.0-insiders.f3fdda2

Let me know if you run into any issues!

It works for my case, thanks for your help, have a good day🫡

[alsguimaraes]

I have tested it too, works fine for me.

[rossipedia]

0.0.0-insiders.f3fdda2 LGTM here 👍