You suddenly get this errer when upgrading WordPress:
Fatal error: Call to a member function do_all_hook() on a non-object in yoursitepath/wp-includes/plugin.php
I fought this last night for about ninety minutes until after reading all the threads on WP.org I figured it out:
Solution: DELETE OR RENAME THE FILE wp-content/object-cache.php
Whether you upgrade automatically or manually, the wp-content directory usually remains constant because that’s where all your customization resides.
This current version apparently does not need that file, in fact it breaks the installation. Somewhere they missed this in their testing.
Are you a WordPress developer that needs a little help? Contact me – I love troubleshooting.