Dynamic listener registration (instance registration) - Connections via the Listener to the Database [TNS-12526 - TNS-12527 - TNS-12528 ]
If you are using dynamic listener registration (instance registration). The instance does not register with the listener until you mount the controlfile. Without sysdba, Net service name using SID or Net service name using SERVICE_NAME with UR=A . RMAN requires a static listener entry and the tnsnames.ora should not contain FAIL_OVER=ON or LOAD_BALANCING. Just a plain vanilla dedicated server connection. RMAN-00554: initialization of internal recovery manager package failed RMAN-04005: error from target database: ORA-12528: TNS:listener: all appropriate instances are blocking new connections