HTTP request to express backend using Postman is throwing unexpected end of form (multipart form data)

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I am sending a multipart/form-data request to my API-backend(in google functions) using postman. In the request, I am sending two fields and one file. The request is processed by Multer/busboy, which throws the error - Unexpected end of the form. Here is my request from the postman in raw form:

POST /app/api/projects/newproject HTTP/1.1
Content-Type: multipart/form-data; boundary=XXX
User-Agent: PostmanRuntime/7.29.0
Accept: */*
Postman-Token: a339b8c1-caa3-4629-8adf-d20967f84
Host: my-projectxxx.cloudfunctions.net
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Cookie: connect.sid=s%3A3h93yTISWRf4cibUG-8Ra3HpqV_iznVz.GhVvgAynx1RuwTyzjCCAlb%2FspGgTzf%2F%2F6VJrkGvNJ
Content-Length: 718115
 
--XXX
Content-Disposition: form-data; name="file"; filename="aliens.png"
Content-Type: image/png
<aliens.png>
--XXX
Content-Disposition: form-data; name="name"
Content-Type: text
John
--XXX
Content-Disposition: form-data; name="is_photo_changed"
Content-Type: text
1
--XXX--
 
HTTP/1.1 500 Internal Server Error
access-control-allow-credentials: true
access-control-allow-origin: http://localhost:3000
content-security-policy: default-src 'none'

And here is the error recorded in my API-backend log:

Unexpected end of form at Multipart._final (/workspace/node_modules/busboy/lib/types/multipart.js:588:17) at callFinal (node:internal/streams/writable:694:27) at prefinish (node:internal/streams/writable:723:7) at finishMaybe (node:internal/streams/writable:733:5) at Multipart.Writable.end (node:internal/streams/writable:631:5) at onend (node:internal/streams/readable:693:10) at processTicksAndRejections (node:internal/process/task_queues:78:11)

It works in the local run but throws an error after being deployed and used in google cloud functions. Any issue with the request? ANy alternative of the postman to test?

google-cloud-functions express node.js http
1 Answers

There must be an empty line between the headers and the content, for example:

--XXX
Content-Disposition: form-data; name="name"
Content-Type: text

John
--XXX

And the lines in the multipart request body must end with CRLF, not just LF.

The following code demonstrates this:

express().post("/", multer().fields([]), function(req, res) {
  res.json(req.body);
})
.listen(80, function() {
  http.request("http://localhost", {
    method: "POST",
    headers: {"Content-Type": "multipart/form-data;boundary=XXX"}
  }).end(`--XXX
Content-Disposition: form-data; name="name"
Content-Type: text

John
--XXX--`.replace(/\n/g,"\r\n"))
  .on("response", function(r) {
    r.pipe(process.stdout);
  });
});

Removing the empty line before John or removing the .replace leads to "Unexpected end of form" errors in multer.

user_164629500
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