In Spotlight for Oracle when doing an Explain for a query under "Top SQL"/"SQL Details", you can get the following errors:
ORA-04045: error during recompilation/revalidation of PUBLIC.DEPTH
ORA-00980: synonym translation is no longer valid in table ExplainPlan
Dropping Spotlight user didn't help.
Make sure Spotlight user has SELECT ANY TABLE privileges.
Drop the public synonym PUBLIC.DEPTH.