=====================
Alert Log
=====================
** 2015-08-28 15:50:17.578 4132 krsh.c
Error 1031 received logging on to the standby
*** 2015-08-28 15:50:17.578 869 krsu.c
Error 1031 connecting to destination LOG_ARCHIVE_DEST_2 standby host 'MANGO'
Error 1031 attaching to destination LOG_ARCHIVE_DEST_2 standby host 'MANGO'

===========
ARCH Trace
============
OCISessionBegin failed. Error -1
.. Detailed OCI error val is 1031 and errmsg is 'ORA-01031: insufficient privileges
'
OCISessionBegin failed -1
.. Detailed OCI error val is 1031 and errmsg is 'ORA-01031: insufficient privileges

==========
Solution
==========

The password files must be same in standby and production that means sys password must be same.

Either you recreate or scpp the latest password file.

On Production
cd $ORACLE_HOME/dbs
scp orapwdProd1 standby:$ORACLE_HOME/dbs/orapwProd1DR


Note:- While copying ensure the password file name must be the db unique name of standby