Apple Pay "payment not completed"

Dear Apple Support,

I am writing to seek assistance with an issue I am facing while implementing Apple Pay in my app. I have integrated the Apple Pay feature in my app but unfortunately, I am encountering an error message that says "Payment not completed" when users try to complete a transaction using Apple Pay.

I have attached a screenshot of the error message for your reference. Could you please help me identify the root cause of the issue and provide me with guidance on how to resolve it?

I would appreciate your prompt response as this issue is impacting the user experience of my app. Thank you for your assistance.

Best regards,