ORA-39701: database must be mounted EXCLUSIVE for UPGRADE or DOWNGRADE

Problem:

In cluster environment, I was not able to start database in upgrade mode:

SQL> startup upgrade

ORACLE instance started.
Total System Global Area 1996486272 bytes
Fixed Size		    8898176 bytes
Variable Size		  704643072 bytes
Database Buffers	 1275068416 bytes
Redo Buffers		    7876608 bytes
Database mounted.
ORA-00603: ORACLE server session terminated by fatal error
ORA-01092: ORACLE instance terminated. Disconnection forced
ORA-39701: database must be mounted EXCLUSIVE for UPGRADE or DOWNGRADE

The following also did not work:

SQL> startup mount exclusive

ORACLE instance started.
Total System Global Area 1996486272 bytes
Fixed Size		    8898176 bytes
Variable Size		  704643072 bytes
Database Buffers	 1275068416 bytes
Redo Buffers		    7876608 bytes
Database mounted.

SQL> alter database open upgrade;
alter database open upgrade
*
ERROR at line 1:
ORA-00603: ORACLE server session terminated by fatal error
ORA-01092: ORACLE instance terminated. Disconnection forced
ORA-39701: database must be mounted EXCLUSIVE for UPGRADE or DOWNGRADE

Solution:

Change parameter cluster_database to FALSE, and startup in upgrade mode:

$ sqlplus / as sysdba

SQL> startup nomount;

SQL> alter system set cluster_database=FALSE scope=spfile sid='*';

SQL> shutdown immediate;

SQL> startup upgrade

ORACLE instance started.
Total System Global Area 1996486272 bytes
Fixed Size		    8898176 bytes
Variable Size		  704643072 bytes
Database Buffers	 1275068416 bytes
Redo Buffers		    7876608 bytes
Database mounted.
Database opened.

After finishing your work, don’t forget to return cluster_database parameter to TRUE and restart your database:

SQL> alter system set cluster_database=TRUE scope=spfile sid='*';