Validity / URI provides useful information?

Started at: 2021-10-27 15:03:54 UTC
Finished at: 2021-10-27 15:03:54 UTC

The endpoint returns some contents in text/turtle and application/rdf+xml, but the content negotiation failed as the Content-type of the response contradicted the Accept header of the request. Please check the server settings of your SPARQL endpoint.