Looks jsxImportSource is not loaded from tsconfig.json after upgrading to v5

[durchanek]

My tsconfig.json includes:

"jsx": "react-jsx",
"jsxImportSource": "@emotion/react",

before upgrading to v5, everything went smooth, after the upgrade using css in className results in

You have tried to stringify object returned from `css` function. It isn't supposed to be used directly (e.g. as value of the `className` prop), but rather handed to emotion so it can handle it (e.g. as value of `css` prop).

Adding react({ jsxImportSource: '@emotion/react' }), to vite.config.ts fixes the issue, so it may be that jsxImportSource is not loaded from tsconfig.json, which should be the case according to the documentation? Or any other idea what may cause this?

Edit: According to #9, this may be a regression.

[umeraamir69]

Yeah. @vitejs/plugin-react@5.0.0 (Aug 7 2025) stopped reading compilerOptions.jsxImportSource from tsconfig. Emotion then treated css as a className string, which is the error you got.

The line you added is the right workaround:

react({ jsxImportSource: '@emotion/react' })

It was fixed 12 days later in 5.0.1: #726

Bump @vitejs/plugin-react to 5.0.1 or later and you can drop the option. 5.x and 6.x still read the tsconfig that applies to the file being transformed.

If it still fails after the bump, the file is probably outside that tsconfig include (or a project reference). The plugin only sees the config for the file it is compiling.