Validity / URI provides useful information?

Started at: 2020-11-21 08:40:42 UTC
Finished at: 2020-11-21 08:40:43 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.