Missing '\r\n' in last boundary of FormData

[viwydev]

Bug Description

When we send a POST request containing a FormData with fetch, the server never responds (as if still waiting for data). We end up going into timeout.

Reproducible By

const form = new FormData();
form.append('hash', 'abc123deadbeef');

let timer:any ;
const resp = Promise.race([
fetch('http://localhost:3000/api', {
method: 'POST',
body: form
}),
new Promise((_,rejection) => timer = setTimeout(rejection, 10000, exception))
]).finally(() => clearTimeout(timer)) ;

Expected Behavior

The last boundary should end with a new line '\r\n' allowing the server to know that all data has been sent.

Logs & Screenshots

Environment

Node v22.15.0

[mcollina]

Thanks for reporting!

Can you provide steps to reproduce? We often need a reproducible example, e.g. some code that allows someone else to recreate your problem by just copying and pasting it. If it involves more than a couple of different file, create a new repository on GitHub and add a link to that.

[KhafraDev]

this looks similar to fdeccc2

[viwydev]

Indeed, it looks very similar... Apparently NodeJS version 22 LTS includes the version 6.9 of the library... Hence the persistence of the problem on my side.

[KhafraDev]

node -p "`node: ${process.version}, undici: ${process.versions.undici}`"
node: v22.15.0, undici: 6.21.2

It seems like the commit didn't make it into the v6.21.2 release

#4210