NeilSanderson

I have the same problem on a site I have run for many years, maritimeradio.org, which uses WP 4.6.1 and the Twenty Ten theme. The site has no posts, only pages.

I have deactivated all plugins.

My permalinks were set to “Post Name” and always worked fine. But yesterday when I edited a page and clicked Update I got a 404 page.

Resaving Permalinks made no difference.

But after changing Permalinks to “Plain”, if I edit a page and click Update no changes are saved and I get taken to my All Posts page in WP admin.

Clearing browser cache has no effect.

Not very advanced, I can assure you. :{-)

Sorry, don’t understand that. But after doing some cleanup in my site directory (while I was generating a child theme as a potential solution) my site mysteriously reverted to WP 3.2.1 (I think it was) then back to 3.3.1 and everything works. I really have no idea what happened. I’ve had this issue for months, but it seems to be working OK at the moment.

Have you considered restricting category visibility by user role?

The Category Visibility plugin at https://ryowebsite.com/?p=46 allows you set a user level for each category on your blog (e.g. give each category a number from 1-10). The plugin then grants access according to the following: Administrator: 10, Editor: 7, Author: 2, Contributor: 1, Subscriber: 0. Unregistered users are also level 0.

I use it and it seems to work fine. My only quibble is that a user can post to a category with a user level higher than their own, even though they cannot see such psotings on the site.

Presumably you could also use Role Manager plug in if you wanted to have additional roles with different access levels.