When we are connecting to Oracle via the listener and we reach our process limit, we're getting an ORA-12519: TNS:no appropriate service handler found. Looking at the the trace file for the event, it's showing an ORA-00020: maximum number of processes (%s) exceeded [where %s is our process limit of course].
What would cause Oracle to throw the misleading error message instead of the one for the real problem?
(I would have added a tag for ora-00020 but I don't have enough rep to add a new one.)