ORA-04021 timeout occurred while waiting to lock object

Error : ORA-04021 timeout occurred while waiting to lock object


Solutions:


1. Look in V$SESSION_EVENT and V$SESSION_WAIT to see what the session is waiting on.
2. Use the V$LOCKED_OBJECT view to find out if anyone else is locking the object.
3. Check  DB links which aren't working correctly.

Kill the relevant sessions if needed.