文档解释
ORA-38800: Cannot start Redo Apply on the open physical standby database
Cause: An attempt was made to start Redo Apply on an open physical standby database instance.
Action: Make sure the primary database is at compatibility 11.0.0 or higher. The redo logs to be recovered on an open physical standby database must be generated at compatibility 11.0.0 or higher. If you have any redo below 11.0.0 to be applied on the standby, you must apply them on a mounted standby before restarting recovery on an open standby when the log format advances to 11.0.0 or higher. If this is a RAC standby database, make sure the ACTIVE_INSTANCE_COUNT parameter is not set.
ORA-38800错误是一种ORACLE系统错误，表明不能在打开的物理备不数据库上启动重做应用。
官方解释
常见案例
一般处理方法及步骤
1、关闭物理备库，执行shutdown immediate，然后启动重做应用；
2、执行alter database recover managed standby database disconnect from session;
3、关闭备库日志传送服务，执行alter system set log_archive_dest_state_2=defer scope=both；
4、执行shutdown abort，重启物理备库；
5、重新启动日志传送服务，执行alter system set log_archive_dest_state_2=enable scope=both；
6、执行alter database recover managed standby database finish;
7、若需要恢复至特定SCN，执行alter database recover managed standby database using current logfile to scn ;
