Cannot drop table from schema

Question

I am trying to use a simple "Drop Table" Statement in PL/SQL Developer on some tables, but they won't drop. The tables are quite large, but I've never had this problem before. After over half an hour, this error is returned: ORA-04021: timeout occurred while waiting to lock object . Things that I have tried:

• Restarting PL/SQL Developer
• Deleting other tables (My schema is not full and have previously had a lot less space)

Answer 1

Please try:

to find sid: select * from v$locked_object;

to find serial#: select * from v$session where sid= "sid_from_the_previous_query";

to kill session: alter system kill session 'sid, serial#';

Or if you are just one user just try commit or rollback.