Dear jdpennmd, Some websites only support certain browsers for their own reasons. You could also try deactivating any add-ons for that websites. I hope this solves your problem! Ivo

Not helpful if Firefox isn't working to make itself compatible with all websites, at least those that have been identified as not compatible.

Hi jdpennmd, I haven't heard about a problem with Delta; is this a known issue for numerous Firefox users? Firefox is still one of their supported browsers: https://www.delta.com/content/www/en_US/support/browser-compatibility.html

I assume the issue is that (like many companies) they outsource payment processing to a dedicated service. There needs to be a complicated data sharing dance between the two sites to make it work. It sounds like you have the worst case scenario: the payment processor was able to charge you, but when you were passed back to Delta, the evidence of the payment wasn't available to the Delta site.

(Over the years, I've had two cases of doubled charitable donations where the site said the payment didn't come through the first time -- after I unblocked everything and tried again, it worked -- but actually they both worked, the site just didn't realize it the first time.)

Without obtaining details about how exactly that information was supposed to be passed back to Delta, it's difficult to point you toward a particular issue/solution. However, some possibilities are:

• Third party cookies not fully enabled
• Local/offline storage not fully enabled
• HTTP headers modified or trimmed
• Background request blocked or modified

It would be great if Delta's website team could work with Mozilla to identify any problems with the less common Firefox configurations (automatic private browsing, higher levels of content blocking). I don't think they would invest the extra time to test with add-ons, though, so for that we're probably on our own.