Error message after update to 2.3.4

-- url of the page with the problem -- : 5-elemente.org
-- HikaShop version -- : 2.3.4
-- Joomla version -- : 3.3.6
-- Error-message(debug-mod must be tuned on) -- : Notice: Undefined property: stdClass::$product_group_after_purchase in /www/htdocs/xxxxxxx/xx/plugins/hikashop/group/group.php on line 77

Hi,
I get this error message after I finished the last step of the checkout:
Notice: Undefined property: stdClass::$product_group_after_purchase in /www/htdocs/xxxxxxxx/xx/plugins/hikashop/group/group.php on line 77

It started after I updated Hikashop to 2.3.4. Everything seems to work, but it is very irritating for the customer to get this error message at the end of his purchase.
What to do?
Best
Roger

Hi Jerome,
I can't find the plugin 'user group after purchase'. I only have 'HikaShop - Vendor group after purchase', but if I deactivate this one, nothing changes and the error message still occurs. I tried to update HikaShop via Joomla extention manager, but received an error.
What to do?
Roger

Found it! Sorry, I looked for the wrong plugin.
Switching off did the job.
Thanks
Roger