Symptoms

When trying to perform the request to add files to the transaction in Postman, it fails with HTTP 400 Bad Request and the following details:

The passed parameters have an invalid value: "Missing content-type boundary" 

Cause

The 'Content-Type': 'multipart/form-data' header from the request configuration is automatically set by the uploader.

Resolution

Check the Headers tab. If the 'Content-Type': 'multipart/form-data' header is present there, please try disabling/removing it, so that the request will be as follows: