Oracle Message ORA-00023 - session references process private memory; cannot detach session

ERRORsession references process private memory; cannot detach session
CAUSEAn attempt was made to detach the current session when it contains references to process private memory.
ACTIONA session may contain references to process memory (PGA) if it has an open network connection, a very large context area, or operating system privileges. To allow the detach, it may be necessary to close the sessions database links and/or cursors. Detaching a session with operating system privileges is always disallowed.