ORA-01035: ORACLE only available to users with RESTRICTED SESSION privilege

Sessions are returned this error while connecting to instances(s) that are running in restricted mode. DBAs may enable restricted sessions to perform some maintenance tasks or in any other needed situation. We can query (g)v$instance to find out if an instance has restricted mode enabled.

SQL> select logins from gv$instance;   LOGINS ---------- RESTRICTED

An instance can be put in restricted mode at startup, or restricted mode can be enabled or disabled while an instance is running.

SQL> shutdown immediate Database closed. Database dismounted. ORACLE instance shut down.   SQL> startup restrict ORACLE instance started.   Total System Global Area 5016387584 bytes Fixed Size                  3842376 bytes Variable Size            1258294968 bytes Database Buffers         3741319168 bytes Redo Buffers               12931072 bytes Database mounted. Database opened.   SQL> select logins from gv$instance;   LOGINS ---------- RESTRICTED

SQL> alter system disable restricted session;   System altered.   SQL> select logins from gv$instance;   LOGINS ---------- ALLOWED   SQL> alter system enable restricted session;   System altered.   LOGINS ---------- RESTRICTED