I don't know why it occurred, but revoking SELECT ANY DICTIONARY from public caused connections to the DB to hang.
DECLARE
BEGIN
FOR l IN (select privilege from dba_sys_privs where privilege in ('SELECT ANY DICTIONARY') and grantee='PUBLIC')
LOOP
EXECUTE IMMEDIATE 'REVOKE '||l.privilege||' FROM PUBLIC';
END LOOP;
END;
/
Any insight into the problem would be appreciated.
Thank you