Symptoms
When we tried to deployed K2 project below error appear.
"Notification Service: Task Error: System.InvalidCastException: Unable to cast object of type 'System.DBNull' to type 'System.Byte[]'."
also when we tried to deployed old version or tried to deploy other projects the same error appear.
Diagnoses
a cold fix is present to resolve the issue
Resolution
Issue resolved after applying a coldfix. Please contact K2 Support to request this coldfix.