[V4] Illegal instruction when using beta inside Docker

[npezza93]

What version of Tailwind CSS are you using?

v4 beta 9

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

docker and ruby

What version of Node.js are you using?

🤷

What browser are you using?

For example: N/A

What operating system are you using?

linux

Reproduction URL

Dockerfile

# syntax=docker/dockerfile:1
# check=error=true

FROM docker.io/library/ruby:3.4.1-slim AS base

RUN apt-get update -qq && \
    apt-get install --no-install-recommends -y curl build-essential git pkg-config && \
    rm -rf /var/lib/apt/lists /var/cache/apt/archives

RUN curl -L -o bin/tailwindcss https://github.com/tailwindlabs/tailwindcss/releases/download/v4.0.0-beta.2/tailwindcss-linux-x64 && \
    chmod a+x ./bin/tailwindcss

RUN ./bin/tailwindcss --help

command: docker buildx build --platform linux/amd64 --file Dockerfile.tw .
Describe your issue

When trying to execute the beta executable in x86 for linux, it errors with '0.054 Illegal instruction'

[Robert344Humphries]

You're encountering an "0.054 Illegal instruction" error when running the Tailwind CSS v4.0.0-beta.2 executable on an x86 Linux system. This issue My Great Lakes is likely due to CPU architecture compatibility. To resolve this, ensure the binary matches your CPU architecture, consider building Tailwind CSS from source, use a stable version, and ensure your Docker configuration is correct.

[sgerov]

not sure if it's your case but I was getting this on Apple Silicon while targeting amd64 platform.

What fixed it for me is changing the Docker Desktop VM settings from Apple Virtualization framework to Docker VMM. (I didn't try with QEMU):

[pzgz]

Everyone using tailwindcss within docker should be cautious, till now, v4.0.3, might still have issue in docker env.

Not only for Apple Silicon, I am running into this issue on a X64 server with ubuntu 20 installed. tailwindcss cli is reporting Illegal instruction (core dumped), waste me a whole day for uprading and have to reverted back to tailwindcss

[flavorjones]

I've had several users of the downstream package tailwindcss-ruby complain about issues that seem like they may be caused by this:

• Problem with tailwidncss binary on x64 N5105 flavorjones/tailwindcss-ruby#54
• TailwindCSS v4 - upgrade experience report rails/tailwindcss-rails#450 (comment)
• Tailwind 4: Can't compile on Docker linux/amd64 flavorjones/tailwindcss-ruby#49

@philipp-spiess tagging you because you were involved in the bun Musl support conversation and may have some insight?

If it's helpful, so far the users that have reported the issue are on various hardware:

• Intel Celeron n5105
• Intel Xeon Skylake - x86_64 (64-bit)
• Heroku servers (unknown)

[thecrypticace]

Not sure if it's your case but I was getting this on Apple Silicon while targeting amd64 platform.

Ah, Rosetta does not support virtualizing all x86_64 instructions so I guess this makes sense.

If it's helpful, so far the users that have reported the issue are on various hardware:

CPU release dates:
Intel Celeron n5105: Q1 2021
Intel Xeon Skylake: Q3 2017
Heroku: no idea either

I'm a bit surprised that the Celeron CPU is reporting illegal instruction errors. Maybe it's also a virtualization thing though?

My guess is that we'll have to use (or otherwise provide) "baseline" builds for Linux x64 which is unfortunate (they're slower) but I don't see any other way around this. We had to do the same thing for the Windows x64 build so people could run it through Window's ARM emulation layer.

[pzgz]

@flavorjones @thecrypticace

For my case, I ran into this issue with a Dell R410 server, with Intel XEON E5620, for sure it's pretty old.

Since @flavorjones was talking about bun musl support, which I can also provided feedback. I was trying to migrating my project to rails 8, and selected bun. But it failed on the same box with same error Illegal instruction (core dumped). I used to think it's about ubuntu 18, but after I upgraded it to ubuntu 24, the issue persisted, so I realized it might not be issue from OS. So I decided not to go with bun and stick with pnpm, but block by tailwindcss v4 upgrade with same error

[thecrypticace]

@pzgz If you're still seeing issues with an npm-installed build that may mean the compiler is auto-vectorizing to at least AVX instructions for Oxide. I'll have to look and see what it'd take to disable that.

[thecrypticace]

Also I looked into it and the Celeron CPU does not support AVX at all — only SSE 4.2. (even tho it was released 10 years after the first processors with AVX shipped from Intel 😱)

[pzgz]

@pzgz If you're still seeing issues with an npm-installed build that may mean the compiler is auto-vectorizing to at least AVX instructions for Oxide. I'll have to look and see what it'd take to disable that.

Thanks and Yes, I did switched to npm install build and still fail.

[npezza93]

Fwiw that repro dockerfile up above was being run using orbstack on an m2 mac