What does the 400 Bad Request mean when you are using a Sage 200 API endpoint?
400 Bad Request
This occurs if the data that you are sending over is malformed or contains invalid fields and values. The API will attempt to return meaningful error messages relating to the cause of the first error it encounters. It is common for this to occur if incorrect foreign IDs are supplied in the body of a request.
https://developer.columbus.sage.com/docs#/uk/sage200extra/accounts/gs-what-makes-up-an-api-request
The 400 Bad request status code indicates that the server was unable to process the request due to invalid information sent by the client. In other words, the client request needs modification. https://www.uniprot.org/help/rest-api-headers
Resolution
You should check your API endpoint request and verify if there is any invalid information sent to the Sage 200 API server.