Please disable *all* plugins. Does the problem go away? If so, turn them back on one at a time until you find the culprit.
Thanks for your response, Steve. I disabled all my plugins and cleared my site and browser caches; checked in Chrome and FF but no change – I still get a new window opening with “Oops! That Page Can’t be Found” after I press the Save Menu button.
if you switch to the twentysixteen theme?
I switched to 2016 theme and there was no change. I still get “Oops! That page can’t be found” when I press the Save Menu button. I again deactivated all my plugins – no change.
The message you’re getting is from a content template, not an admin page, so that’s just downright confusing. There are couple of options:
1. Maybe this is a corrupt install. Can you reinstall WP from Dashboard->updates? Maybe a file is missing.
2. After that, please make sure you really have all plugins disabled,
3. It could be a caching issue. Are you using Cloudflare? Does your host do any caching outside of what is done by plugins?
I’m not using Cloudflare, only a WP caching plugin. I’ve contacted my hosting service and they found some kind of security file that was blocking something, which they whitelisted. Unfortunately that didn’t help either. I decided to create a Secondary menu to replace the faulty one, which I have just finished and tested – it works! I’ll be using that menu as my main menu now. Many thanks for your input, it is much appreciated!
