I am suddenly getting a 503 error:
"Service Temporarily Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later."
when attempting to add pages to the menu. All other functions are working fine. Tried adding different pages, tried replacing the nav-menus.php page since that comes up in the URL bar, still keep getting same error.
Tried same function on different site using same theme on same server, works fine.