500 Internal server Error (nothing are adding in navigation menue)
I am using latest version of wordpress with Lapa theme . I installed plugins like Smush,Swift,WP fastest cache and Gtmetrix. Now when I go to Appearence-> Menue and add desired or randomly Links thent it returns 500 internal server error. How to remove this ? I tried by deactivate plugins and changing theme but nothing happen , How to resolve this issue ?