Upgraded to the latest version and got a “fatal error”.
Disabled all plug-ins by renaming the plug-ins folder.
Disabled Redirection plug-in as suggested elsewhere on this forum.
Fatal error problem solved and also the 404 error solved.
I had the same problem as described in the original post. The instructions to disable plug-ins worked for me and I also discovered that the Redirection plug-in was the culprit.
Upgrading to the latest version of WP also fixed my 404 error on the home page, which was somehow caused by a contributor’s post to my blog.
I appreciate the help — it has been a long day!
