admin.ajax.php file not found

I had a problem saving, and the logger showed that the file admin.ajax.php wasn’t found. The file was in the correct location and I was stumped. I don’t host this site, so it has an unusual setup that I don’t control. I thought it might be about memory or timeouts.

The host solved it – perhaps this will help others

“This was ModSec blocking you from making any updates to the web pages.
So normally you have to log in with Cpanel, disable ModSec, do the changes to the webpage and then enable ModSec again.

“I have added ModSec rules to Apache to allow WordPress admins to make changes without doing the above mentioned steps so this will solve the issue for all your sites.”