Can't add Products from Back Office

[diamondcouture]

I was able to successfully add my Categories from the Back Office, but when I try to add new Products from the Back Office I'm getting sent to a blank white page. When debug is turn on I see the following Error message.....

 

ClassNotFoundException in PassConfig.php line 48:

Attempted to load class "ResolveReferencesToAliasesPass" from namespace "Symfony\Component\DependencyInjection\Compiler".

Did you forget a "use" statement for another namespace?

 

I'm not sure how to rectify..Please assist. Thanks in advance.

 

I'm using version 1.7.2 in Prestashop with the Classic Theme for now.

Edited August 31, 2017 by diamondcouture (see edit history)