For the past week I have noticed that my KCSUser.Activeuser() is often getting timeouted, which is quite worrying. By that I mean that after random period of time from 1 hour to 1 day my active user just becomes nil and I get "errorError Domain=KCSServerErrorDomain Code=401 "Invalid credentials. Please retry your request with correct credentials"

Is it some method which causes this or there is something up with servers.

Good morning Grisha,

There shouldn't be anything wrong with the servers causing this issue.  If you turn debug logging on for your project?  This may lead us to a better understanding of what's happening here.

http://devcenter.kinvey.com/ios/guides/troubleshooting#Debugging

Please let me know if you have any other questions,