Cannot create new user Vtiger 7.4.0 error This page isn’t working xxx is currently unable to handle this request.

Hello when i try to create new user on vtiger 7.4.0 it shows me this error while creating new user

http://xxxx/index.php?module=Users&parent=Settings&view=Edit, fill all the information needed, when i click save and it redirect me here -> http://xxxx/index.php This page isn’t working xxx is currently unable to handle this request. HTTP ERROR 500

Someone can help me please, im new on vtiger.