v4 upgrader removing the content of all files in my project

[nexxai]

What version of Tailwind CSS are you using?

⚡️? 78% ➜ npx @tailwindcss/upgrade --version
≈ tailwindcss v4.1.13

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

Vite: 6.3.6

What version of Node.js are you using?

For example: v21.7.3

What browser are you using?

n/a

What operating system are you using?

macOS Tahoe 26.0

Reproduction URL

This is not a rendering issue, it's a problem with the @tailwindcss/upgrade package, so I'm not sure how to provide a "reproduction" but happy to do so if someone can explain.

Describe your issue

I realize this is going to sound crazy, but I swear it's happening and I can't figure out why. When I run `npx @tailwindcss/upgrade" to upgrade my app from v3 to v4, it deletes every file in my project tree. Not just CSS files, but literally every file.

Specifically, it happens during the "Migrating templates..." step. Originally, it looked like it was hung, but when I killed the process, I checked my git tree and thousands of files had been deleted. Thankfully, I had run a commit right before I ran the updater so I could revert without issue, but I suspect this is not expected behaviour.

In this example, I show that there are no changes to be made, I run the upgrader, and then it's showing all of these files having been deleted (it would delete more if I didn't CTRL-C out of the upgrader).

2:36:03 PM in ipms on  filament-v4-upgrade via 🥟 v1.2.22 via  v8.4.12
⚡️? 78% ➜ git status
On branch filament-v4-upgrade
nothing to commit, working tree clean

2:36:05 PM in ipms on  filament-v4-upgrade via 🥟 v1.2.22 via  v8.4.12
⚡️? 78% ➜ npx @tailwindcss/upgrade
≈ tailwindcss v4.1.13

│ Searching for CSS files in the current directory and its subdirectories…

│ Migrating stylesheets…

│ ↳ Migrated stylesheet: `./resources/css/app.css`

│ Updating dependencies…

│ ↳ Updated package: `tailwindcss`

│ ↳ Updated package: `@tailwindcss/postcss`

│ ↳ Updated package: `@tailwindcss/vite`

│ ↳ Updated package: `prettier-plugin-tailwindcss`

│ Migrating templates…

^C

2:36:17 PM in ipms on  filament-v4-upgrade [!] via 🥟 v1.2.22 via  v8.4.12 took 8s
⚡️? 78% ➜ git status
On branch filament-v4-upgrade
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   .editorconfig
        modified:   README.md
        modified:   _ide_helper_models.php
        modified:   app/Casts/Markdown.php
        modified:   app/Console/Commands/AddDuesToAllCommand.php
        modified:   app/Console/Commands/AddInstructionalVideosCommand.php
        modified:   app/Console/Commands/ImportContest2024Command.php
        modified:   app/Console/Commands/ImportMembersCommand.php
        modified:   app/Console/Commands/MigrateDbEngineCommand.php
        modified:   app/Enums/ClassifiedAdContactType.php
        modified:   app/Enums/ClassifiedAdType.php
        modified:   app/Enums/Config/DuesFrequency.php
        modified:   app/Enums/ContestEntryAgeClass.php
        modified:   app/Enums/ContestEntryRanking.php
        modified:   app/Enums/ExternalMembershipOrganization.php
        modified:   app/Enums/InstructionalVideoPanel.php

no changes added to commit (use "git add" and/or "git commit -a")

2:36:19 PM in ipms on  filament-v4-upgrade [!] via 🥟 v1.2.22 via  v8.4.12
⚡️? 78% ➜

I'm not really sure what else to do. I tried downloading and compiling the package myself to try and understand why it's even thinking it should touch any non-CSS file but I'm getting this error when I try to pnpm run build the main tailwindcss project:

error[E0463]: can't find crate for `std`
  |
  = note: the `wasm32-wasip1-threads` target may not be installed
  = help: consider downloading the target with `rustup target add wasm32-wasip1-threads`

even though I've already confirmed that target is installed:

⚡️? 78% ➜ rustup target add wasm32-wasip1-threads
info: component 'rust-std' for target 'wasm32-wasip1-threads' is up to date

Any help would be greatly appreciated. Thanks!

[wongjn]

Consider providing a git repo of a project that reproduces the issue and we can take a look for you.

[nexxai]

Consider providing a git repo of a project that reproduces the issue and we can take a look for you.

Will do. Give me a few minutes. Thanks!

[nexxai]

@wongjn Ok so I created this repo: https://github.com/nexxai/tailwind-upgrader-bug

And I realize I misspoke (and will edit the title as soon as I finish typing this out) but it's technically not "deleting" the files, but rather removing all of their content.

For example:

If you run npx @tailwindcss/upgrade on this project, it's very easy to do a git status and see all the files that were changed to be a single empty line.

I included one specific canary file (app/Enums/NeverDeleteThisFile.php) and even its contents are removed; something that should obviously never happen.

Thanks for looking into this!

[wongjn]

The empty files seem to be because you've stopped the upgrader halfway through. When testing, it shouldn't take as long as it does. I think it does for several reasons:

• You have a lot of files in public which seem to be large, minified code. If these are "vendor" files that you don't need to upgrade, I'd suggest temporarily moving them out before upgrading.
• Flowbite. Having "./node_modules/flowbite/**/*.js", in the content array in tailwind.config.js causes the upgrader to scan and process all the files in the Flowbite package. Though really this is third-party anyway so the upgrader perhaps shouldn't touch this. Again, perhaps remove "./node_modules/flowbite/**/*.js", from the content array before upgrading.

Doing these two things drops the time taken for the Migrating templates… to a few seconds.

[nexxai]

That worked. Thanks a lot @wongjn !

[FrederikGottlieb]

For anyone else experiencing this in the future.

(upgrade tool deleting content in all project files, even files not included in the tailwind content array. IE: even php files and text files etc)

I had the same issue and deleting my compiled frontend .js files solved it. (in my case everything in /public/js)

(I'm assuming somehow references in those files were making the upgrade tool go crazy despite there being no references to them in the tailwind content config)