Do you have any error logs?
I had an issue on my original 1.3.4 -> 2.0 upgrade on a CentOS 7 box as well. I needed to delete the phalcon.so file from the 1.3.4 install then install 2.0.
now, phalcon2.0 is install successful...but, Another problem has appeared, is about Mongo ODM , i cann't to use it, is throw exception :
Fatal error: Uncaught exception 'BadMethodCallException' with message 'Wrong number of parameters' in /var/www/html/iot/apps/app/controllers/UserController.php:21 Stack trace: #0 [internal function]: Phalcon\Events\Manager->fire('collectionManag...') #1 [internal function]: Phalcon\Mvc\Collection\Manager->initialize(Object(Faeva\Common\Models\App)) #2 /var/www/html/iot/apps/app/controllers/UserController.php(21): Phalcon\Mvc\Collection->__construct() #3 [internal function]: Faeva\App\Controllers\UserController->createAppAction() #4 [internal function]: Phalcon\Dispatcher->dispatch() #5 /var/www/html/iot/public/index.php(66): Phalcon\Mvc\Application->handle() #6 {main} thrown in /var/www/html/iot/apps/app/controllers/UserController.php on line 21
please help me to solve...thanks