Paypal 1&1 returning error 500 at payment completion

[myth vapes]

When my customers try to make a payment and confirm order, the paypal module brings back a 500 server error message.

 

I dont do scripting and i have my modules set up through 1&1 so they host all.. need help as i cannot run my business

 

Is there any steps to follow inside the prestashop app on 1&1?

I am using version 1.6.1.13