primary is not shipping archivelogs to standby database. tnsping and remote connections working fine from primary database. But still getting this error messae ORA-12154 in primary alert log / trcae files while shipping archives to standby.

as per Doc ID 1240558.1 the ARC processes read the tnsnames.ora only once during process initialization, any updates to the tnsnames.ora after startup will not be known to the ARC process and hence the error
ORA-12154: TNS:could not resolve the connect identifier specified
is reported when the ARC processes try to resolve the (new) value for the ‘service’ attribute.

to resolve this error i killed all the arc process of primary database at os level and immediately it respawnned. now archives are shipping properly to standby database