Oracle Dataguard trouble shooting

Oracle Dataguard not working then try the basics of stop and start if not refer to the link below which recommends to restart primary server.
http://scn.sap.com/thread/2016335 - Archived Log is not shifting from Primary to DR

execute this command in Primary server

ALTER SYSTEM SET log_archive_dest_state_3='DEFER' SCOPE=BOTH;

ALTER SYSTEM SET log_archive_dest_state_3='ENABLE' SCOPE=BOTH;


Related topics on Oracle Dataguard error and trouble shooting
recover automatic standby database until cancel;
alter database recover cancel


DG

select sequence#, first_time, next_time from v$archived_log order by sequence#;

select sequence#, applied from v$archived_log order by sequence#;

select process, status, sequence# from v$managed_standby;

select database_role, protection_level from v$database;

select database_role, protection_level from v$database;

alter system set log_archive_dest_state_3=defer;

alter system switch logfile;

SELECT MESSAGE FROM V$DATAGUARD_STATUS;


SQL> SELECT MESSAGE FROM V$DATAGUARD_STATUS;

MESSAGE
------------------------------------------------------------------------

ARC0: Archival started
ARC1: Archival started
ARC0: Becoming the 'no FAL' ARCH
ARC0: Becoming the 'no SRL' ARCH
ARC1: Becoming the heartbeat ARCH
Attempt to start background Managed Standby Recovery process
MRP0: Background Managed Standby Recovery process started
Managed Standby Recovery not using Real Time Apply
Clearing online redo logfile 1 R:\ORACLE\DPF\ORIGLOGA\LOG_G11M1.DBF
Clearing online redo logfile 1 complete
Media Recovery Waiting for thread 1 sequence 42190

MESSAGE
------------------------------------------------------------------------

Fetching gap sequence in thread 1, gap sequence 42190-42289
FAL[client]: Failed to request gap sequence
 GAP - thread 1 sequence 42190-42289
 DBID 3620481324 branch 595624108
FAL[client]: All defined FAL servers have been attempted.

16 rows selected.

select * from (select sequence#,applied,first_time from v$archived_log
order by first_time desc)
where rownum <10;

select process,status,thread#,sequence#,block#,blocks from v$managed_standby;

select sequence#, name, archived, applied from  v$archived_log
where sequence# like '%42286%';


@ECHO OFF
replace W:\test.txt U:\oracle\DPF\temp /A



Help full notes on WAIT_FOR_GAP DG

http://anoopbal.blogspot.nl/2012/03/falclient-failed-to-request-gap.html
https://kr.forums.oracle.com/forums/thread.jspa?threadID=2171232
https://cn.forums.oracle.com/forums/thread.jspa?threadID=2233823
http://www.dba-oracle.com/t_detect_redo_log_gaps.htm
http://docs.oracle.com/cd/B28359_01/server.111/b28294/trace.htm#CACBEFAD
https://scn.sap.com/thread/1876345