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

 If there is an archive gap and dataguard database is not fully in synch with the primary database, initiating DGMGRL and connecting to the database would immediately show ORA-16724 with the configuration. This can be seen bellow.

DGMGRL for Linux: Version 11.2.0.4.0 - 64bit Production  Copyright (c) 2000, 2009, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected. DGMGRL> show configuration  Configuration - TEST DG configuration   Protection Mode: MaxPerformance   Databases:       DB_PROD  - Primary database       Error: ORA-16724: cannot resolve gap for one or more standby databases     DB_DG - Physical standby database   Fast-Start Failover: DISABLED Configuration Status: ERROR DGMGRL> show database verbose 'DB_DG'; Database - DB_DG   Enterprise Manager Name: DB_DGP   Role:                    PHYSICAL STANDBY   Intended State:          APPLY-OFF   Transport Lag:           1 day(s) 13 hours 20 minutes 23 seconds (computed 8 seconds ago)   Apply Lag:               1 day(s) 13 hours 32 minutes 48 seconds (computed 0 seconds ago)   Apply Rate:              (unknown)   Real Time Query:         ON   Instance(s):     DB_DG1 (apply instance)     DB_DG2   Properties:       DGConnectIdentifier             = 'DB_DG'       ObserverConnectIdentifier       = ''       LogXptMode                      = 'ASYNC'       DelayMins                       = '0'       Binding                         = 'optional'       MaxFailure                      = '0'       MaxConnections                  = '1'       ReopenSecs                      = '300'       NetTimeout                      = '30'       RedoCompression                 = 'DISABLE'       LogShipping                     = 'ON'       PreferredApplyInstance          = ''       ApplyInstanceTimeout            = '0'       ApplyParallel                   = 'AUTO'       StandbyFileManagement           = 'AUTO'       ArchiveLagTarget                = '0'       LogArchiveMaxProcesses          = '4'       LogArchiveMinSucceedDest        = '1'       DbFileNameConvert               = ''       LogFileNameConvert              = '+REDO_DG1/DB_PROD, +REDO_DG1/DB_DG, +REDO_DG2/DB_PROD, +REDO_DG2/DB_DG'       FastStartFailoverTarget         = ''       InconsistentProperties          = '(monitor)'       InconsistentLogXptProps         = '(monitor)'       SendQEntries                    = '(monitor)'       LogXptStatus                    = '(monitor)'       RecvQEntries                    = '(monitor)'       ApplyLagThreshold               = '0'       TransportLagThreshold           = '0'       TransportDisconnectedThreshold  = '30'

 This error clearly shows that some of the archived redo logs are not available on the standby site to apply, thus causing a gap. To solve this issue, make sure that all the required archived logs are available on the physical standby database so that they could be applied to the database. If not available, you can manually copy the archived logs from the primary database. If the required archived logs have been deleted, and/or cannot be restored, you might want to perform an incremental restore to synchronize the dataguard with the primary.