refObjects is a table that is used to look up the typename of a specific content object using its objectid.
Damaged refObjects Table
If you find yourself manually removing or migrating records in the database, you may find that the refObjects table will get out of synch with the records represented in the system.
refObjects Repair Utility
There is a dedicated utility for repairing this table available here:
ADMIN > COAPI Management > Fix RefObjects Table