Product:
Cognos Controller 8.5.1

Symptom:
Error message when running Optimize of database inside Cognos Controller Client.

Message:
Error occurred at removal of temporary VFP files. VFP DLL file missing.

Cause:
The password for the service account that runs Cognos Controller COM+ was changed.

But only the IBMCOGNOSCONTROLLER part was updated from the Cognos Controller Configuration program.
The separate IBMCOGNOSVFP part is not updated automatic.

Solution:
Login to the Cognos Controller Server
Go to Control panel – Administrative Tools – Component services
Expand the COM+ applications until you see two entry’s that begin with IBMCOGNOS….
Right Click on the IBMCOGNOSVFP and select properties
Select the Identity tab
Change the username and password to the correct one at “This user”.
Click OK
Restart the COM plus service.
Restart the COGNOS CONTROLLER BATCH SERVICE.
Try again to run optimize of the database.

Above is not on all Cognos Controller installations. Common is that you have only one IBMCOGNOSCONTROLLER com application.