Symptoms
After an upgrade from 4.6.6 to 4.6.11 the host server would not start:
Error 2001 Error starting the host server: could not find stored procedure 'HostServer.GetEncryptionInfo'
Diagnoses
Client's db was corrupted and in a bad state. The client did not have a backup.
Resolution
Using the consolidation tool to create a new db and transfer the data to it. After, running a reconfigure.