Oracle Clusterware is restarting database “” | shut down instance “” of database “” | start up instance “” of database “”

When I used data guard broker to switchover primary database to standby database sometimes broker writes “Oracle Clusterware is restarting database”  … hangs and times out.

The problem was that database was not registered with srvctl.

srvctl add database -d db_unique_name -o oracle_home
srvctl add instance -d db_unique_name -i instance_name1 -n node_name1
srvctl add instance -d db_unique_name -i instance_name2 -n node_name2

instead of db_unique_name, oracle_home , instance_name1, node_name1,  instance_name2, node_name2 enter values according to your database.