In reply to Peter Cralen.

I'm able to access the frontend with PHP7 and WP 4.4b1 with no problem, but when trying to access the backend, I'm presented with:

Fatal error: Uncaught Error: Call to undefined function wp_installing() in /wp-includes/update.php:25 Stack trace: #0 /wp-includes/update.php(598): wp_version_check() #1 /wp-includes/plugin.php(503): _maybe_update_core('') #2 /wp-admin/admin.php(168): do_action('admin_init') #3 /wp-admin/index.php(10): require_once('/home/xxx/...') #4 {main} thrown in /public_html/wp-includes/update.php on line 25

This error goes away just by changing my PHP to 5.x