Bug Description

When using the HTTP Request node (v4.4) to send a binary file via multipart-form-data, the request is sent but the file is not properly attached. The receiving API returns 400 - "No file field in request".

The same request works correctly when executed via curl, confirming the API endpoint is functioning properly.

Additional observation: In the Webhook node, I set "Field Name for Binary Data" to invoice_file, but the output still shows the binary data under data0. This may be related - if the binary property key isn't being set correctly, the HTTP Request node may not be finding the binary data at the expected location.

Screenshot attached showing:

<img width="1788" height="1434" alt="Image" src="https://github.com/user-attachments/assets/43b1c11c-8740-43b2-8aaf-99bbb58a2ab1" />

"Field Name for Binary Data" set to invoice_file Output showing binary data under data0 instead

To Reproduce

1. Create a workflow with binary data available (e.g., PDF from a previous node)
2. Add an HTTP Request node configured to send the file via multipart-form-data
3. Execute the workflow
4. API returns 400 error: "No file field in request"

Node Configuration { "parameters": { "method": "POST", "url": "https://example.com/api/endpoint", "authentication": "genericCredentialType", "genericAuthType": "httpBearerAuth", "sendBody": true, "contentType": "multipart-form-data", "bodyParameters": { "parameters": [ { "parameterType": "formBinaryData", "name": "file", "inputDataFieldName": "data0" } ] } }, "type": "n8n-nodes-base.httpRequest", "typeVersion": 4.4 }

Error Response: { "errorMessage": "Bad request - please check your parameters", "errorDescription": "No file field in request", "errorDetails": { "rawErrorMessage": ["400 - "{\"error\":\"No file field in request\"}\n""], "httpCode": "400" } }

Expected behavior

The file should be attached to the multipart-form-data request with the field name "file", and the API should receive it correctly.

Actual behavior: The request is sent, but the file field is missing from the request body. The API returns a 400 error indicating no file was received.

Debug Info

The API works correctly with curl: curl -X POST "https://example.com/api/endpoint"
-H "Authorization: Bearer TOKEN"
-F "file=@/path/to/document.pdf"

Operating System

Linux Ubuntu LTS 24.4

n8n Version

2.17.3

Node.js Version

v24.14.1

Database

PostgreSQL

Execution mode

main (default)

Hosting

self hosted