Entries form in control panel won't display if I have a Matrix field enabled
This usually happens if xdebug is installed with the default nesting limit. You can either disable xdebug as PHP itself does not have a function nesting limit,

change the setting in your php.ini:

xdebug.max_nesting_level = 400


or in your PHP code:

ini_set('xdebug.max_nesting_level', 400);