1- Check both primary and standby role

SQL> select name, open_mode, database_role from v$database;

SQL> select status, instance_name, database_role,open_mode from v$database, v$instance;

2- Check the archived sequence in standby

SQL> select thread#,max(sequence#) from v$archived_log group by thread#;

SQL> SELECT ARCH.THREAD# Thread, ARCH.SEQUENCE# Last_Sequence_Received,
APPL.SEQUENCE# Last_Sequence_Applied, (ARCH.SEQUENCE#-APPL.SEQUENCE#) Difference
FROM
(SELECT THREAD# ,SEQUENCE# FROM V$ARCHIVED_LOG WHERE (THREAD#,FIRST_TIME ) IN
(SELECT THREAD#,MAX(FIRST_TIME) FROM V$ARCHIVED_LOG GROUP BY THREAD#)) ARCH,
(SELECT THREAD# ,SEQUENCE# FROM V$LOG_HISTORY WHERE (THREAD#,FIRST_TIME ) IN
(SELECT THREAD#,MAX(FIRST_TIME) FROM V$LOG_HISTORY GROUP BY THREAD#)) APPL
WHERE
ARCH.THREAD# = APPL.THREAD#
ORDER BY 1;

3- In standby side,stop the mrp process

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

4- Bounce the database and keep in mount stage,

SQL> shut immediate
SQL> startup mount

4- Convert to snapshot standby database

SQL> alter database convert to snapshot standby;

5- Open the standby database in READ/WRITE mode

SQL> alter database open;

6- Check the DATABASE_ROLE and OPEN_MODE

SQL> select status, instance_name, database_role,open_mode from v$database, v$instance;

7- In Standby Side,bounce and mount the database

SQL> shut immediate
SQL> startup mount

8- Convert the snapshot standby database to physical standby database

SQL> alter database convert to physical standby;

9- Bounce the database

SQL> shut immediate
SQL> startup 

10- Check the standby database_role and mode

SQL> select status,instance_name,database_role,open_mode from v$database,v$Instance;

10- Enable the MRP process

SQL> alter database recover managed standby database disconnect from session;