Okay I recently upgraded to WordPress 4.0 on one of the sites I maintain. I upgraded it like I do with all my WordPress sites by doing the following:
1. deactivate all plug-ins
2. switch to a theme that was packed in with WordPress – I switched to twentyfourteen
3. update WordPress through the built-in updates
When it finished the site was okay on the backend, and I could see all the menu items (they all stayed in the database). But when I tried to view them in the front end I got 404 errors for everything. Menu pages, menu single items, everything in the menu database went to a 404. So I did a rollback to 3.92 and everything became view-able again and didn’t go to a 404.
I’d like to upgrade to WordPress 4.0 but I want to stick with the Sunrise theme. I use a child theme to modify it as I need. Any ideas? The only thing I could come up with is that something happened when I switched to the twentyfourteen theme and then upgraded. I’m afraid to try leaving the Sunrise-child theme on and then upgrading, at least until I hear back from you guys. Thanks in advance.