Cornerstone is NOT compatible with php 7.1+. On multiple sites, if I upgrade cornerstone, I can no longer access the WP admin page, but ONLY if that site is running PHP 7.1 or higher. For sites running php 7.0, everything is fine.
ABSOLUTELTY POSITIVE this is an error with cornerstone because the error log states; Call to undefined method ReflectionType::getName() /chroot/home/qwicktri/qwicktrim.com/html/wp-content/plugins/cornerstone/includes/classes/Plugin.php:106
Please address this asap