Error message seen in picture below appears usually when CUSTOMTOOLS database has been moved to another server.
Error message is harmless and it appears because CUSTOMTOOLS error messages don't exist in SQL Server.
Problem can be fixed by following these instructions:
1. Launch CUSTOMTOOLS Administration Tool, that is usually installed in one of the CUSTOMTOOLS workstations or in the server where CUSTOMTOOLS database service is running.
2. Select the option "Create Database" and create the new empty database named "DUMMY-DATABASE", for example (name is not important but it is better to name the database so that indicates that database is not in use). When creating a database, uncheck the option "Set as active" to keep the existing database active.
3. When database has been created, please remove it from "registry" by selecting the database with right mouse button, selecting the option "Unregister" and accepting the removing from registry by pressing "Yes".
See THIS VIDEO to see the above steps in detail.