ORA-02019: connection description for remote database not foundThis error can be seen when you specify a nonexistent or mistyped database link name or when invoking a synonym that points to an object containing a nonexistent database link.
As the former case is trivial, let's look at the latter:
say you have a db link called remote_db:
CREATE SYNONYM remote_table_a FOR table_a@remote_db;
then at a later time you drop the db link (supposing the connection closed, otherwise you'll get ORA-02018):
DROP DATABASE LINK remote_db;
now, when you attempt to run a query on remote_table_a, you get:
ORA-02019: connection description for remote database not foundClearly, if you don't know that behind the synonym there is a db link, this error can be puzzling, especially if the synonym is public and the underlying definition has not been created by you...
See message translations for ORA-02019, ORA-02018 and search additional resources.