The below things are main reasons to get the issues in Dataguard environment
make sure below params set properly or not.
log_archive_config='dg_config=(prim,stand)'
log_archive_dest_1='location=/arch/prim/ valid_for=(all_logfile,all_roles) db_unique_name=prim'
log_archive_dest_2='service=stand valid_for=(online_logfile,promary_role) db_unique_name=stand'
proper listener and tnsnames configuration
space on mount point and permissions
finally archive is availabe on primary or not