I did not install any recent plugins, but here is a list of my plugins.
Whenever clicking view on one of my custom posts that previously worked I would get a page not found. I thought this might be a template issues, so i double checked my php file template was named single-[nameofpost].php and that was correct and went unchanged and was also working before the update. I then deleted that template and set the custom post to use a default template and it still was not showing up.
NEXT I deleted my cookies and tested on another computer both results were still the same and displaying a page not found.
THEN I proceeded to uninstall the plugin and even went to far as to delete ALL of my custom posts and taxonomies. I then reactivated everything and made a FRESH new post type and taxonomy, still same results.
I finally fixed it by resetting my plugin folder...(so painful!)
- going into my ftp, navigating to /wp-content/ folder
- creating a folder called plugin-temp
- moving ALL plugins located in the plugin folder to the new plugin-temp folder
- the plugin folder was now empty
- logging into wp-admin of the site
- clicking plugins, and received many wordpress errors indicating the missing plugins
- finally went back to ftp, and moved all the plugins back into the normal plugin folder
- re-activated every plugin
it now works again..for now! Still not sure what happened but I also lost all my custom posts.