May I please “bump” this topic as I too have spent hours trying to resolve this without success. I cannot do a one-click update from WP 4.0.1 to 4.1. Whenever I try, I get a Page Not Found at http://www.mydomain.com/wp-admin/update-core.php?action=do-core-upgrade.
The file update-core.php is present and correct.
I have checked all permissions as detailed in the thread above.
I have tried with all plugins de-activated – without success.
Thanks to anyone who can help!
