2898813 - ORA-16724: cannot resolve gap for one or more standby databases

There is a gap in the Redo Sequence on the Standby database.

 
The error itself is visible in different places as seen below:

1. Alert Log of the Primary Database
   
   ...
   

   2020-02-28 15:02:20.868000 +01:00
   Errors in file /oracle/DG1/diag/rdbms/dg1_north/DG1/trace/DG1_arc1_28323.trc:
   ORA-00308: cannot open archived log '/oracle/DG1/oraarch/DG1arch1_251_913812350.dbf'
   ORA-27037: unable to obtain file status
   Linux-x86_64 Error: 2: No such file or directory
   Additional information: 3
   <<NOTE, above error is present only if the file is physically not available anymore or there is a problem to access the file>>
   ...
   RFS[3]: Assigned to RFS process (PID:18406)
   RFS[3]: Opened log for thread 1 sequence 252 dbid 1895179966 branch 913812350
   Archived Log entry 255 added for thread 1 sequence 252 rlc 913812350 ID 0x71e14b21 dest 2:
   RFS[3]: Opened log for thread 1 sequence 253 dbid 1895179966 branch 913812350
   Archived Log entry 256 added for thread 1 sequence 253 rlc 913812350 ID 0x71e14b21 dest 2:
   Fetching gap sequence in thread 1, gap sequence 251-251
   ...

2. Alert Log of the Standby Database
   
   ...
   

   FAL[client, ARC1]: Error 1034 connecting to dg1north.world for fetching gap sequence
   FAL[client, ARC1]: Error 12541 connecting to dg1north.world for fetching gap sequence
   FAL[client, ARC1]: Error 1034 connecting to dg1north.world for fetching gap sequence
   Fetching gap sequence in thread 1, gap sequence 251-251
   FAL[client]: Failed to request gap sequence 
   archivelog gaps.

   ...
   
   
   
3. Data Guard Broker Command Line Tool (DGMGRL) (if Broker is configured)
   
   ...
   

   DGMGRL> show configuration

   Configuration - dg1

   Protection Mode: MaxPerformance
   Members:
   dg1_north - Primary database
   Error: ORA-16724: cannot resolve gap for one or more standby databases

   dg1_south - Physical standby database

   Fast-Start Failover: DISABLED

   Configuration Status:
   ERROR (status updated 26 seconds ago)

   ...
   
   
4. Data Guard Broker Log / drc<DBSID>.log (if Broker is configured)
   
   ...
   

   Found unresolvable gap for database dg1_south.
   Data Guard Broker Status Summary:
   Type Name Severity Status
   Configuration dg1 Warning ORA-16607
   Primary Database dg1_north Error ORA-16724
   Physical Standby Database dg1_south Success ORA-00000

   
   ...
   
   

• SAP Netweaver
• Oracle RDBMS 10g and upwards
• Data Guard (Standby Database)

data guard, broker, standby, primary, ORA-16724, ORA-16607, ORA-00308, ORA-27037, DGMGRL, FAL, ARCH, Fetching gap sequence, request gap sequence, gaps, archivelog
, KBA , BC-DB-ORA , Oracle , Problem