cannot add dependency job for unit firewalld.service ignoring unit firewalld.service is masked

This issue have been a change of display manager so only it came. 

first we need to know which kind of display manager we are using so following command will so the 
display manager status.

systemctl status display-manager.service

then we need to update the display manager service 

systemctl reenable gdm.service

now issue have been fixed.