[oracle] ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired

In my case, I was quite sure it was one of my own sessions which was blocking. Therefore, it was safe to do the following:

  • I found the offending session with:

    SELECT * FROM V$SESSION WHERE OSUSER='my_local_username';

    The session was inactive, but it still held the lock somehow. Note, that you may need to use some other WHERE condition in your case (e.g. try USERNAME or MACHINE fields).

  • Killed the session using the ID and SERIAL# acquired above:

    alter system kill session '<id>, <serial#>';

Edited by @thermz: If none of the previous open-session queries work try this one. This query can help you to avoid syntax errors while killing sessions:

  • SELECT 'ALTER SYSTEM KILL SESSION '''||SID||','||SERIAL#||''' immediate;' FROM V$SESSION WHERE OSUSER='my_local_username_on_OS'