Zend certified PHP/Magento developer

Magento 2 – Invalid Form Key for new storeview

I created a new storeview and noticed that I can’t log in as a customer. It works on the main store view perfectly fine. There are no errors in the server and magento logfiles.

I always get: “Invalid Form Key. Please refresh the page. “

I disabled ALL third party modules and changed my theme to magento luma, but I still get the error.

Magento Version: 2.3.4-p2