We don't use the database per tentant functionality. It also doesn't clarify why it does work with a get or create.
Thanks ismcagdas, I didn't knew there was a logfile for that. When opening the logfile the problem was immediately clear. "Only one complex type allowed as argument to a web api controller action". Strange thing is that I didn't change that code and sometimes it worked and sometimes it didn't.
You have made up my day!!!
Thanks that did the trick
