1.6 cannot add to cart products of certain category

[eloman89]

Hi guys here again

This time we have this error on or shop, throws a default pop up error message, it only affects to category id '198'

prestashop version 1.6.1.14 

link to our shop : bilbotruke.net

this is the error message:

Impossible to add the product to the cart.
textStatus: 'parsererror'
errorThrown: 'SyntaxError: Unexpected token < in JSON at position 0'
responseText:

Fatal error: Uncaught exception 'Exception' with message 'Forbidden chars in cookie' in /var/www/vhosts/bilbotruke.net/httpdocs/classes/Cookie.php:176 Stack trace: #0 /var/www/vhosts/bilbotruke.net/httpdocs/modules/ganalytics/ganalytics.php(841): CookieCore->__set('ga_cart', 'a:1:{i:5740;a:1...') #1 /var/www/vhosts/bilbotruke.net/httpdocs/classes/Hook.php(591): Ganalytics->hookActionCartSave(Array) #2 /var/www/vhosts/bilbotruke.net/httpdocs/classes/Hook.php(546): HookCore::coreCallHook(Object(Ganalytics), 'hookactionCartS...', Array) #3 /var/www/vhosts/bilbotruke.net/httpdocs/classes/Cart.php(214): HookCore::exec('actionCartSave') #4 /var/www/vhosts/bilbotruke.net/httpdocs/classes/Cart.php(1071): CartCore->update() #5 /var/www/vhosts/bilbotruke.net/httpdocs/controllers/front/CartController.php(300): CartCore->updateQty(1, 5740, 0, 0, 'up', 0) #6 /var/www/vhosts/bilbotruke.net/httpdocs/controllers/front/CartController.php(73): CartControllerCore->processChangeProductInCart() #7 /var/www/vhosts/bilbotruke.net/httpdocs/class in /var/www/vhosts/bilbotruke.net/httpdocs/classes/Cookie.php on line 176

[eloman89]

more info

after clicking the 'add to cart' button and throw that error, I noticed it's being added to the cart after reloading the page, 

this error does not affect to all products on this category, only with the newest ones 

there's also an error when trying to delete them from the cart 'unable to delete' or similar, again after refreshing, it gets deleted

i hope you can help us thx in advance