I have been experiencing a mysterious error whenever I activate any plugin on WP 4.2.1:
Fatal error: Cannot redeclare maybe_create_table() (previously declared in /wp-admin/install-helper.php:52) in /wp-admin/includes/upgrade.php on line 1616
The plugin is activated though when I navigate away from the error screen.
To my surprise, there is a lot of entries about this error when searching google, but not a single solution is posted, or a cause of this error. I have looked through every single search result.
There is this 7 year old trac ticket discussing
maybe_create_table() being declared in two instances but that is marked as solved.
What in the world is this? What is the cause of it?