How can I configure n8n's HTTP Request node to authenticate with the FileRun API?

Below is a checklist of things to verify and adjust in your HTTP Request node configuration so that your request mimics the successful curl call:

1. Use the Correct Body Format

The curl command sends data in a URL-encoded form (using –d). In the HTTP Request node, under Send Body make sure you:

• Select Form URL Encoded as the Body Content Type.
• Configure the body parameters as key/value pairs exactly as expected by filerun’s API:
  • username: n8n
  • password: redacted$
  • scope: upload
  • client_id: redacted
  • client_secret: redacted
  • redirect_uri: https://n8n.redacted.de
  • grant_type: password

Avoid leaving angle brackets (< and >) around the URL if they were only used in the curl example for clarity.

2. Confirm the Request Method and URL

• Verify that you have set the Method to POST.
• Double-check the endpoint URL to ensure there are no typos (for example, confirm it is exactly:
  https://filerun.redacted.de/oauth2/token/).

3. Check Content-Type Headers

Even if you choose the “Form URL Encoded” option, verify that the node sets the Content-Type header to application/x-www-form-urlencoded. If not, add it manually under Send Headers.

4. Watch for Special Characters

• Ensure that any special characters or symbols (like the $ in your password) are correctly passed without unexpected escaping.
• When testing manually, try hardcoding the same value to ensure it’s not causing the server to reject the request.

5. Troubleshoot the Response

A 400 error (“Bad Request”) typically means the API did not like the request format. In n8n you could use the “Retry on Fail” option or switch temporarily to the HTTP Request node’s Response Mode settings (for example by returning the full response headers and status) to get more insight into what the API is complaining about.

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By configuring the node in these ways, your workflow request should closely match the working curl command. If you still encounter issues, try the following:

• Manually recreate the key/value pairs in the node (instead of relying on the imported configuration) to ensure none of the formatting has been transformed unexpectedly.
• Refer to filerun’s API documentation for any nuances in the required parameter names or values.

This approach should set you on the right path to resolve the error and successfully retrieve the access token.