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

SQL> alter system set cluster_database=false scope=spfile;

[oracle@dcdb01 22674697]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.2.0.4.0 Production on Sun May 15 18:56:08 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup upgrade
ORACLE instance started.

Total System Global Area 6413680640 bytes
Fixed Size                  2265224 bytes
Variable Size            3472887672 bytes
Database Buffers         2919235584 bytes
Redo Buffers               19292160 bytes
Database mounted.
ORA-01092: ORACLE instance terminated. Disconnection forced
ORA-39701: database must be mounted EXCLUSIVE for UPGRADE or DOWNGRADE
Process ID: 27450
Session ID: 194 Serial number: 3


SQL> startup nomount;
ORA-24324: service handle not initialized
ORA-01041: internal error. hostdef extension doesn't exist
SQL>
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options
[oracle@dcdb01 22674697]$
[oracle@dcdb01 22674697]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.2.0.4.0 Production on Sun May 15 18:58:42 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup nomount;
ORACLE instance started.

Total System Global Area 6413680640 bytes
Fixed Size                  2265224 bytes
Variable Size            3472887672 bytes
Database Buffers         2919235584 bytes
Redo Buffers               19292160 bytes
SQL> alter system set cluster_database=false scope=spfile;

System altered.

SQL> shut
ORA-01507: database not mounted


ORACLE instance shut down.
SQL> startup upgrade
ORACLE instance started.

Total System Global Area 6413680640 bytes
Fixed Size                  2265224 bytes
Variable Size            3472887672 bytes
Database Buffers         2919235584 bytes
Redo Buffers               19292160 bytes
Database mounted.
Database opened.

SQL>