Symptoms
The error was thrown from a custom webpart utilizing our Blackpearl API
Diagnoses
It was found out that there are multiple duplicate entries in ClaimRealm, ClaimDataType and ClaimDataTypeMapping
Resolution
Resolved after we clear all those duplicate entries followed by Blackpearl service restart. STRONGLY suggest to log a ticket to get helps from K2 Support to help on this. This involves direct Database entries modification.