Thank you for the information! I think I fixed my incorrect implementation. I was creating the PaymentRequest prior to the user clicking the button. I waited until they clicked it to call show, but that's clearly not correct (at least for Windows, it did work before on Mac). Now that I wait to construct the object after the click, I see the graphic that can be scanned, and scanning it does show a payment sheet on my iPad. This works both with Edge on Windows and Chrome on Mac. I really appreciate your help! The No "Link: rel=payment-method-manifest" HTTP header found at "https://www.apple.com/apple-pay/". error is still present, but I see that on the demo site as well. I don't believe it's affecting functionality at this time. I am glad to see that the merchant validation event is triggered in Edge, so I suspect I will be able to complete my implementation with the PaymentRequest API. However, I am still concerned that W3C has marked it as deprecated. https://www.w3.org/TR/merchant-validation/ W3C actually goes so far as to say it was removed from the spec, they only even have a document on it because some browser engine (at least Chrome, I suppose) already implemented it. This is my primary concern about the stability of the API. If I deploy this solution to my eCommerce platform, am I going to be surprised one day to find that the merchant validation event no longer fires on the latest version of Chrome? Or am I going to find the Apple SDK has changed to a different event or setup? I don't have much experience with W3C, so I don't really know what the warning means, but it looks severe. Can you speak to this specific feature and your expectations of its availability in the future? Thanks again!

I would check your cert.pem file. That sounds like it's not in PEM format. If it is, you should be able to open it in a text editor and see something like "BEGIN CERTIFICATE" near the top. PEM files are ASCII, but they are base64 encoded. You won't be able to read any of the details, but there shouldn't be any special characters.