Update. I recently updated to FF v83.0b4 and had another crack at this paypal cart thing. Funny thing. It worked the first time. Problem solved? Not so fast. Went to try it a second time - just to be sure - the old, buggy behavior presented itself again.

This time i cleared the www.paypal.com cookie and the cart worked as it should again.

One would think this would be paypal related but i've tried to duplicate the problem on Safari but i can't oddly enough.

In conclusion (from my perspective) if you are using a retail site that employs the paypal cart system (ie. it opens a new tab for your cart contents at paypal.com) and you have trouble adding more than one item to it consider clearing the www.paypal.com cookie and trying the experience again.

Cheers, Stephen

Hi Stephen, Firefox has a number of protective features that can interfere with sites being able to put 1 and 1 together. These including using "container tabs" to isolate sites from one another, various settings related to cookies, and advanced features such as site isolation and possible about:config changes.

Do you know whether you are using any of these features/changes while interacting with this site?

For example, some sites use local storage instead of or as a supplement to cookies, and if you set Firefox to clear cookies at the end of your session, those sites may not work properly. This was an issue with Outlook mail on the web. Not sure if it might be affecting PayPal or this particular site, but I noticed I have a cookie exception for https://paypalobjects.com so maybe it does?

Example of fixing that issue with Outlook: https://support.mozilla.org/questions/1282001

Hi, Thanks for replying. I don't have any unusual or advanced settings ticked in my privacy and security settings. Specifically i do not have "Delete cookies and site data when firefox is closed" checked which upon reflection would mitigate this issue b/c the "fix" is to delete the paypal cookie. In addition I don't have any cookie exceptions either fwiw. All configs are default as i haven't got fancy in any way.

But, yes, I agree this feels like firefox is doing something extra in the name of security by determining something is amiss between what's in the cookie (my past) and what the current state is (my present) that its forcing (ie. instructing paypal) to create new object (cart) each time.

For sure though two tabs for one experience just seems to be asking for trouble in the end - but that's another story.

It's interesting that clearing PayPal cookies makes the cart work again. I wonder if you shop on multiple sites that use PayPal and that causes an issue?