You have Archive Gap in your database.
1. Please check lower and high sequence of archive gap;
select * from v$archive_gap;
2. Check, did you have backup of this archived logs in primary database
RMAN> list backup of archivelog from logseq <lower sequence> until logseq <high sequence>;
2.1 if you have backup then restore this archivelogs. If you are stopped MRP, start MRP
RMAN> restore archivelog from logseq <lower sequence> until logseq <high sequence>;
SQL> alter database recover managed standby database disconnect from session;
2.2 If not any backup, then you must use ROLL FORWARD Standby database using RMAN incremental backups.
Mahir M. Quluzade
As previously posted, you have a GAP. So, you may have to investigate why the Archived logs cannot be applied.
To do so, you may check for the File System if any Archive destination is FULL. Also, you may have to verify the parameters on the PRIMARY and STANDBY site:
sqlplus "/ as sysdba" show parameter fal show parameter dest show parameter config show parameter broker
Check also the Alert log on both Primary and Standby.
If the DATAGUARD BROKER is enabled you may also execute this
dgmgrl show configuration verbose
Also try to "tnsping" the services used in the Archive Destination from both site.
When you are sure that everything is correct then, verify if any Archived logs is missing and try to restore it if possible.
Else if everything is broken, and there's no way to get back the missing Archived logs, you 'll have to "rebuild" the Standby from a new Backup of the PRIMARY.
Hope this help.