409 Conflict Status Code

[YoucTagh]

409 Conflict could be used in case of error when processing a PUT HTTP method.

[larsgsvensson]

To me 422 seems the better choice.
According to RFC 9110 409 Conflict is about conflict of due to the state of the representation (as in version control systems). 422 Unprocessable Content gives the example of "media type is correct and content syntactically OK, but the semantics of the supplied resource are incorrect" which I think is what we intend.

[YoucTagh]

I agree with you. The 422 Unprocessable Content status code seems more appropriate in our case.

I was able to find two other RFCs that refer to this status code: RFC 4918 and RFC 5789. An example of how to use the status code can be found at this link.

The body of the response can be used to indicate the reason for the error and possibly how to fix it. In the case of non-conformance to a SHACL shape graph, I think the validation report can be a good hint.