Error 500 on product page

[twistoon]

Hi

 

I'm getting a lot of errors after an upgrade from prestashop 1.4 to 1.7

The most bothersome is an error 500 when I go to a product page. 

I turned on dev mode, and it seems to be linked to the modules that were installed with 1.4.

- it throws up an error for a module, I disable the module, it throws up another error for that one, disable that, another and so on. 

So far, I've had to disable social sharing, change paypal, and I'm working on the categories now... 

Has anyone had the same problem? Is there any solution? I guess I should have probably found a way to do a fresh install than this "one click upgrade". 

Thank you for any help.