A client's website has 12 pages, but we can both only see 3 of them, even though we have administrator accounts, and creating a new administrator account does not solve the problem.

Screen Options will not open, and if I check the Chrome console, I see:

> Failed to load resource: the server responded with a status of 500 ():
> /wp-admin/edit.php

I can see `/wp-admin/edit.php` exists.

I have removed `/wp-admin` and `/wp-includes` and uploaded fresh copies of these.

I have uploaded a fresh copy of the parent theme, and the child theme is untouched.

If I rename `plugins` to `plugins.temp` the issue remains.

Help appreciated.