Symptoms

Can't create workflows from the UI after reverting K2 from 4.6.11 to 4.6.10. A stored procedure is looking for a parameter which is not getting passed when we try to create a connection to k2 for the code behind.

Procedure of function 'UpdateSccCredential' expects parameter '@PasswordCached', which was not supplied.
 

Diagnoses

When K2 was previously upgraded to 4.6.11, the K2 database had also been upgraded to a matching version 4.6.11 (containing new/different tables/columns/stored procedures) as such it is not possible to revert back to 4.6.10 by just re-installing the 4.6.10 server components. It is likely that the 4.6.10 K2 server/API is expecting a different method/SQL stored procedure parameter than what the 4.6.11 database currently contains.

Usually the steps to reverting would require a restoring of a K2 database backup while it is on version 4.6.10 both the database and the K2 server will need to be of a matching version.

As such, it is recommended that a full database backup is created prior to the upgrading K2 so it can be reverted if necessary.
 

Resolution

Reverting the K2 database back to a matching 4.6.10 version resolved the issue.