SYMPTOM:
When the user updates schema in Strategy Developer 9.x and 10.x, the following error occurs:
Population Exception: The object shown in the following hierarchy no longer exists in schema: - Population Exception: DBMS-DBMSThe object definition is incomplete or inconsistent.
The same error can also happen when the user executes some reports.
CAUSE:
One possible cause is that one or more database instances do not have 'Database connection type as shown below:

ACTION:
Check all database instances to make sure everyone has a database connection type assigned. If the user is not able to launch the Database Instance Editor or having problem re-assigning a database connection type, contact Strategy Technical Support.