When the payment was made in test mode to make a test payment in Shopify, the message ‘There was a problem when adding this card’ was displayed and the test payment could not be made.
Conclusion, it was because they were testing with Shop Pay.
It is highly likely if ‘Shop Pay’ was ticked in the payment settings in the administration panel.
Shop Pay is a PayPal-like wallet payment that applies Shopify Payment’s credit card payment system.
The official documentation also states that Shop Pay test payments are not available.
テストモード機能は、Shopify POSカードリーダー、Shop Pay、またはShop Payの分割払いのテスト決済では利用できません。
Therefore, it was necessary to prepare and test the credit card types in the documentation in order to test payments.
答えはいつも公式ドキュメントですね。
