FormData with invalid Content-Length

[gbrueckl]

I want to upload a file using FormData but it fails with

{"code":"InputStreamIncorrectLengthException","message":"The length of the file input stream does not match the provided length. Expected: '12463', Actual (approximate): '12464.'"}

As I am not setting the Content-Length manually but its set internally by node-fetch, I want to raise this here.
PS: I also tried setting the Content-Length manually to 12463, 12464 and 12465 (the actual length of the UInt8Array) but none worked either

Reproduction

I am using the following code from within a VSCode extension

let formData: FormData = new FormData();
const fileName = uri.path.split('/').pop().split(".")[0];

const arr: Uint8Array = await vscode.workspace.fs.readFile(uri);
const blob: Blob = new Blob([arr]);
formData.append(fileName, blob);

let headers = this._headers;
headers["Content-Type"] = "multipart/form-data";

const config: RequestInit = {
method: "POST",
headers: headers,
body: formData
};
let response: Response = await fetch(endpoint, config);

Expected behavior

Content-Length should be set correctly automatically when using FormData
the code is similar to whats described in the docs: const abc = new File([binary], 'abc.txt', { type: 'text/plain' })

Your Environment

software	version
node-fetch	3.3.2
node	v18.13.0
npm	8.19.3
Operating System	Windows 11

[kirbdee]

unclear if it's a similar issue. but the services i was using is also expectin a multipart/form-data body but was responding with bad request. I then just omitted the content-type for sanity and it seemed to work, this was how the samples used it

https://www.npmjs.com/package/node-fetch#post-data-using-a-file

import fetch, { FormData, File, fileFrom } from 'node-fetch'

const httpbin = 'https://httpbin.org/post'
const formData = new FormData()
const binary = new Uint8Array([ 97, 98, 99 ])
const abc = new File([binary], 'abc.txt', { type: 'text/plain' })

formData.set('greeting', 'Hello, world!')
formData.set('file-upload', abc, 'new name.txt')

const response = await fetch(httpbin, { method: 'POST', body: formData })
const data = await response.json()

console.log(data)

[GeoffreyPlitt]

+1 I am seeing this too.