Oracle data gurad ORA-16416 error

Oracle dg is my own test environment, because the ip is occupied, so I need to change the ip, after changing the ip encountered the following problems, now record.

After changing the ip, I still do the normal master / slave switchover. Due to my carelessness, I did not query the master / slave switchover_status before the switch. I switched directly and found the following error:

Switchover on the host

Randomly queried the following switchover status of master and slave and found:

Lord:

Standby:

In the middle, I thought that there was a problem with the master database, so I restarted the master database. Later, it was found that the listening status of the master and slave libraries was not running:

It is found that the host address is the address before the change, then change the host address, restart listening, reconfigure the tns file, restart the main database and query again:

Display the not allow ed status, view the official website documents and display:

NOT ALLOWED-Either this is a standby database and the primary database has not been switched first, or this is a primary database and there are no standby databases.

SESSIONS ACTIVE-Indicates that there are active SQL sessions attached to the primary or standby database that need to be disconnected before the switchover operation is permitted.

This may be because when I restart the main library, some of the logs in the database backup database are not applied. Execute recover managed in the repository

Query again in the main database:

It has become to standby, and then you can switch between the master and the slave normally.