HTTP Request not sending multipart/form-data with multiple files

Questions
1

Version 1.116.2 running locally on Windows.
I am not able to get a HTTPRequest node using multiple files to properly send a form request. I double-checked using Postman and the files are correct as is the URL I’m sending to. The error from endpoint: 400 - “{"id":"a5e6827e-e6e4-46b1-ac98-995098595ebf","message":"Array cannot be null. (Parameter ‘bytes’)"}”

2

Looked at it again, it looks to me like a bug in n8n’s HTTP POST when trying to do a form post with multiple files.

3

FWIW…chatgpt…

Got it — at this point you’ve proved beyond doubt that:

  • your merge / combine / debug stages all output valid binaries, and

  • the HTTP Request node itself is what throws

    “Array cannot be null”

That error comes from inside n8n’s HTTP-node multipart builder, and it happens when the node tries to hand binary data to its internal formData[] array but the VM isolation prevents the streams from being passed. In short:

:light_bulb: The HTTP Request node simply cannot stream multiple binary fields reliably in the local CLI runtime (sandboxed or not).

So you’ve done everything right — the limitation is in n8n itself.

4

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.