Error message : Unable to resolve domain abc.com while populating domain display cache: no thrown error-- 2600 are seen in system logs while accessing the records in certain tables.
Verify does the instance is domain separated or not.
Validate the sys_domain column value from the problematic table records.
If the instance is not domain separated then the sys_domain filed will redirect you to sys_user_group table.
If the records in a table is holding a non existing domain name and if the system doesn't find a valid match in sys_user_group table then we this error message will be thrown.
Inorder to overcome this issue, you need to modify the sys_domain field value to global for all the records or create a matching entry in the sys_user_group table.