The umbraco version Im currently using is 7.5.14, have been uppgraded from 7.3.x. The presentation part of umbraco is always working without any problems, but the backoffice is acting strange.
When sign in to the backoffice all of a sudden the backoffice stops working and in the web browser console 500 errors are thrown. There is nothing in the umbraco log about the errors or in the event log. When I or any other user is trying to sign in after this has occurred, we cant. In the web browser console there is nothing useful. The only thing it says is that postLogin is throwing 500 error with the message "an error has occurred".
Even when no one is signed in to the backoffice and doing stuff, when a user is trying to sign in the backoffice is throwing 500 erros. The only solution is to recycle the application pool, after restarting the pool we are able to sign in and work in the backoffice again. But the problem can occurre again briefly after restarting the app pool or within an hour or two.
I have been trying to find a solution in many ways but simple cant get rid of the problem.
Edit I discovered that if Im signed in to umbraco backoffice while the problem occurres. There is a Get request to "umbraco/backoffice/UmbracoApi/Authentication/GetCurrentUser" that returns http 500 code. But there is nothing in the logs about the error...
After decompiling the umbraco controller (AuthenticationController), I noticed a connection in the PostLogin function and GetCurrentUser function. They both use Automapper when mapping user information.
Another project that my web application has reference to has a AutoMapper configuration that is used when a certain class is instantiated. The class calls Mapper.Initialize and after that the umbraco backoffice will fail to map its users. Thats why the error occurs arbitrarily.