NotSupportedError: multipart/form-data not supported

[kettanaito]

Bug Description

Getting the following error:

 Promise {
      <rejected> NotSupportedError: multipart/form-data not supported
          at Request.formData (node:internal/deps/undici/undici:2311:19)

Reproducible By

const formData = new FormData()
formData.append('username', 'john.maverick')

const req = new Request('http://localhost', {
  method: 'POST',
  body: formData,
})

console.log(req.formData())

This example uses Node.js globals for Fetch API so I'm not importing any polyfills for neither Request nor FormData.

Expected Behavior

Calling request.formData() must return a Promise that resolves to a FormData instance containing the fields initially supplied to the Request constructor.

Logs & Screenshots

Environment

• Node 18.8.0

Additional context

I've skimmed Undici's source and couldn't find this NotSupportedError instance. I suspect this was indeed unsupported in the past but has been implemented in the newer versions of Node? I'd like to know when this was added, if ever. Thanks.

[KhafraDev]

https://github.com/nodejs/undici/releases/tag/v5.11.0 which seems to have been added in v18.11.0