Impossible to add the product to the cart. textStatus: 'error' errorThrown: '' responseText

[fvl1970]

Hello since 25-12-2018 people who want to add a product to the shopping cart get this message : " Impossible to add the product to the cart. textStatus: 'error' errorThrown: '' responseText" " 

It looks like the product will end up in the shopping cart but the message does scare costumers 

I read that in the past for some people it did help to disable Google Analytics , I did try this but it doesn't work

My Prestashop version is : 1.6.1.11

Can someone help me please