Ok so i have set up a new symfony3 project using :

Vagrant----Virtualbox----PHP56----MYSQL55----UBUNTUTRUSTY64.

Everything was working correctly until i make a "composer update". I have this error message and i cannot do anything now

> 
> Attempted to load class "DOMDocument" from the global namespace
> 
> 
> 

So i found some proposed solution like "install php-xml" but it is already installed with newest version.

Does anyone have a solution or guide me to the right direction to find one

Many thanks 

Nico