How to upload Business Transaction XML (BTX)?

Hi,

when we try to upload a Business Transaction XML (BTX) file as described eg in Upload BTX Files for End-to-End Tracing - REST API Application Development - SAP Library we always receive HTTP status 400 with the message "Wrong content type". We tried without content-Type header and with application/xml and with multipart/form-data .

Anyone a idea?

Thanks,

Wolfgang