[Error] Explain Plan (20: 8): ORA-02019: connection description for remote database not found

I the this error when I select the explain plan button in toad

[Error] Explain Plan (20: 8): ORA-02019: connection description for remote database not found

turn on spool SQL so you can see what’s happening. Sounds like there is an invalid DB Link in the query that you are trying to explain.