I got a long list of deprecated warnings, and the session would not even start, so not even a login screen is displayed.
Deprecated: Assigning the return value of new by reference is deprecated
Warning: The magic method __get() must have public visibility and cannot be static
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent
The solution is to edit config/dmsDefaults.php, find the lines containing
error_reporting(E_ALL & ~E_NOTICE);ini_set('display_errors', '1');ini_set('display_startup_errors', '1');
Below that, add the following line:
error_reporting(0);
Now Knowledge Tree 3.7.0.2 will work again, and hopefully the next version of Knowledge Tree will have fixed all the deprecated PHP things.