HTTP ERROR 500

[Adrian]

I run into a problem and can't find the way out. 

I have installed Prestashop 1.6.1.16,  1.7.0,   1.7.1 and 1.7.2.4

Only 1.6 works, all of the others return HTTP ERROR 500. 

Fatal error: Uncaught Error: Class 'Symfony\Component\Filesystem\Filesystem' not found in /home/vetpoijm/public_html/config/bootstrap.php:50 Stack trace: #0 /home/vetpoijm/public_html/config/config.inc.php(58): require_once() #1 /home/vetpoijm/public_html/index.php(27): require('/home/vetpoijm/...') #2 {main} thrown in /home/vetpoijm/public_html/config/bootstrap.php on line 50

Have no idea hot to fix this. 

I have tried everything I can find on google... so, please, HELP!!!

 

To mention, this is a fresh install of a prestashop online. 

Apache Version	2.4.29
PHP Version	5.6.32
MySQL Version	5.6.38

Edited January 17, 2018 by Adrian (see edit history)