“ORA-01017: invalid username/password; logon denied” While Data Guard Switchover

Data Guard switchover failed with “ORA-01017” error :

DGMGRL> connect /
Connected as SYSDG.

DGMGRL> switchover to STDBYDB;
Performing switchover NOW, please wait...
Operation requires a connection to instance "STDBYDB2" on database "STDBYDB"
Connecting to instance "STDBYDB2"...
ORA-01017: invalid username/password; logon denied

Warning: You are no longer connected to ORACLE.

RESOLUTION

Logon as SYS, then switchover will be successful.

DGMGRL> connect SYS
Connected as SYSDG.
DGMGRL> switchover to STDBYDB;

Performing switchover NOW, please wait...

Operation requires a connection to instance "STDBYDB2" on database "STDBYDB"

Connecting to instance "STDBYDB2"...

Connected as SYSDBA.

New primary database "STDBYDB" is opening...

Oracle Clusterware is restarting database "PRIMDB" ...

Switchover succeeded, new primary is "STDBYDB"