Database version = 11.2.0.3.0

If you get following error while adding a Standby Redo Log (SRL) to a standby database in dataguard configuration:

SQL> alter database add standby logfile group 3 '/logs/test/sbyredo3a.log' size 500M;
alter database add standby logfile group 3 '/logs/test/sbyredo3a.log' size 500M
*
ERROR at line 1:
ORA-01156: recovery or flashback in progress may need access to files


Then it means that first you have to stop the redo apply, add the SRL and then start the redo apply. Best way to do is from dgmgrl like this:

DGMGRL> connect /
Connected.

DGMGRL> edit database 'test' set state='APPLY-OFF';
Succeeded.

SQL> alter database add standby logfile group 3 '/logs/test/sbyredo3a.log' size 500M;

Database altered.

DGMGRL> edit database 'CONPRO_UK' set state='APPLY-ON';
Succeeded.

HTH.