My company has the following problem. We are using the extension "Add free product to cart". The software allows users to create specific rules (conditions). If the conditions are true, then a free product is added to the cart.
We discovered the following problem. We have created three rules which are all checking the values of the products in the cart where category id == 18. if a customer adds more than exact 31 articles to his cart, then the websites html code is getting downloaded instead of getting rendered.
If there are only two rules, then a customer can add exact 47 products to his cart, at 48 the bug starts and the website downloads instead of renders.
I hope you understand the problem. It seems like the extension can't handle more than 94 set-cookie requests or maybe even magento has a cookie limit
I found out that in case of this bug, the value of the header "content type" is application/x-httpd-ea-php70 instead of text/html; charset=UTF-8 and thus the html is getting downloaded.
Can you check if cart data is placed into the cookie?
I've saw a few strange modules working in that way.