That’s great to hear you figured it out, @GateCheckCheryl ! Thanks for following up. If you have any other questions or concerns, please let me know.
Topic summary
Merchants are encountering “There was an error adding this card” when testing payments in Shopify’s test mode, particularly when attempting to use Shop Pay.
Root Causes Identified:
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Shop Pay Auto-Login Conflict: If a checkout email was previously used with Shop Pay, the system automatically attempts Shop Pay login (via SMS code), which is incompatible with test mode. Solution: Click “Checkout as guest” to bypass Shop Pay.
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Shopify Payments Not Deactivated: One user resolved the issue by deactivating Shopify Payments before testing.
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Account-Specific Issues: Some users needed fresh email accounts to successfully test.
Key Limitation:
Shopify staff confirmed that test mode does not support Shop Pay, Shop Pay Installments, or POS card readers. Official documentation suggests creating a Shop Pay account with a vaulted test card (using the 4242 test number), but users report this method fails with the same error.
Current Status:
One user suggests this may be a Shopify bug, as the documented testing method for Shop Pay doesn’t work. The workaround is testing standard Shopify Payments (which should indicate Shop Pay will function correctly) or using real cards on non-development stores.