Some sites are not working because of doing on PHP 5.4+. There are some changes that need to be made, luckily pretty simple. If you haven't modified anything, look at: https://github.com/nabeelio/phpvms_v2. The php70 branch (default, download here: https://github.com/nabeelio/phpvms_v2/archive/php70.zip) is updated to support PHP 7+
If you're on the 5.x version, you should be fine.
Find ~Line 46:
error_reporting(E_ALL ^ E_NOTICE);