"Cannot create proxy" error building Vite + Tailwind v4 app with Cloudflare plugin

[crrobinson14]

What versions & operating system are you using?

@cloudflare/vite-plugin v1.2.4, vite v6.3.5, @tailwindcss/vite v4.1.7

Please provide a link to a minimal reproduction

Reproduction Repro

NOTE: See the comment in vite.config.ts.npm run build works when the plugin is commented out, and breaks when it's active. I did the scaffold and Cloudflare plugin installation in two separate commits. You can see the change by comparing HEAD vs the previous commit.

Describe the Bug

I have a Vite project with a Tailwind v4 config. Running npm run build works locally. But after adding the cloudflare() plugin to vite.config.ts per https://developers.cloudflare.com/workers/vite-plugin/tutorial/#set-up-and-configure-the-react-spa, I receive this error:

error during build:
[@tailwindcss/vite:generate:build] Cannot create proxy with a non-object as target or handler
file: [REDACTED]/apps/web/src/index.css

This error text was reported separately here TanStack/router#4132 but it appears as though while the causes may be the same, the actual issue is different. That report was an issue in tanstack-router related to the new Vite "Environment API" and their issue was fixed in a recent release. Perhaps the same fix is required here? (To be clear: this is not a current issue in tanstack-router, and the repro above does not install it.)

Please provide any relevant error logs

Just the error reported above, on the console.

[schiller-manuel]

this is the issue I created at vite when I debugged the issue in TanStack Start: tailwindlabs/tailwindcss#18002

[jamesopstad]

Thanks for the reproduction. The issue here is that you are using the main field in your wrangler.toml to point to your client entry file. The main field is for pointing to a Worker entry file. If you have a client-side only project then there should be no main field as there is no user Worker.

[crrobinson14]

@jamesopstad I will retest this today with that change, but can that be documented somewhere more clearly, and/or detected by Wrangler? This is a very confusing error if that's the root cause...

[jamesopstad]

Sorry for the confusion. I don't think we could detect this very easily as the main field expects as TS/JS file and that's what you provided. We can take another look at the docs though and see if this could be made clearer.

[crrobinson14]

I know this is closed and don't want to re-open it, but @jamesopstad if you're still monitoring this I just deployed a new Vite project and almost made the same mistake. I realize now what threw me off initially, and there might still be a documentation-improvement opportunity here.

After scaffolding a new/base Vite+React project and attempting to deploy to Workers, you can get this in your logs:

21:40:17.584 | ✘ [ERROR] Missing entry-point to Worker script or to assets directory
-- | --
21:40:17.584 |  
21:40:17.584 |  
21:40:17.584 | If there is code to deploy, you can either:
21:40:17.585 | - Specify an entry-point to your Worker script via the command line (ex: `npx wrangler deploy src/index.ts`)
21:40:17.585 | - Or add the following to your "wrangler.toml" file:
21:40:17.585 |  
21:40:17.585 | ```
21:40:17.585 | main = "src/index.ts"
21:40:17.585 |  
21:40:17.586 | ```

FURTHER DOWN you are told that there is an assets-only approach, but you have to scroll down in the build logs to see it, so it's easy to miss. Perhaps you might adjust this build-side message so the fact that there are two deployment paths here (server-side code will be run vs. static-assets will be served) is more clear in the first sentence or two? "If there is code to deploy" isn't really clear that what's meant is server-side code. To a lot of us, HTML and CSS are "code", so it's not clear that what's really being referenced is an SSR vs SPA choice...