Symptoms

After performing an upgrade of K2 blackpearl and K2 SmartForms from 4.6.6 to 4.6.8 on Windows Server 2008 SP2 (non R2) the following error is being displayed when attempting to access K2 Designer:
An error occurred trying to authenticate the user.
Exception Details:
System.Security.Cryptography.CryptographicException: Keyset does not exist at System.Security.Cryptography.Utils.CreateProvHandle
 

Diagnoses

There is a KB article K2 KB001571 “Known Issue: Resolving a “Keyset does not exist” login error after upgrading to K2 smartforms 1.0.6”:
http://help.k2.com/kb001571
And normally you may resolve this issue following the steps from KB and using K2 Certificate Update Utility which you may download using a link from KB article. But in some cases you may see that this utility does not solve your problem when you use Windows Server 2008 (non R2).
 

Resolution

There is a special version of K2 Certificate Update Utility intended for Windows Server 2008 (non R2) which can be obtained through K2 support request.