Auto upgrade today failed. I deleted the .maintenance file and the upgrade folder. I received the following error when trying to access wp-admin or wp-login:
Fatal error: Call to undefined function is_network_admin() in /home/primal99/public_html/wp-admin/admin-header.php on line 16
I followed the steps for a manual upgrade and received the same error. Any solutions? A rollback feature would be nice for incidents like this.