Square POS SDK throws 'could_not_perform' error

I’m currently using the POS SDK for in-person payments in Japan, and I have a few questions:

If a payment is made for public transportation using the Square POS app, but the “Continue” button is not pressed, is the payment considered completed, even though Square’s data may show it as “uncompleted”?

In the above situation, if I try to accept another payment without pressing “Continue,” will it result in a “could_not_perform” error, preventing me from proceeding until I press “Continue”?

In the event of an incomplete transaction as described above, is it possible to cancel that transaction?

Thank you.

Hey @aya, welcome to the forums!

When a payment is made on the Square POS app, the Point of Sale API will not notify your app of the transaction’s status (completion or failure) until after the device returns to your application. If another payment is attempted before this, you’ll typically get a could_not_perform error. In these cases, the transaction will need to be canceled (or completed) from Square Point of Sale itself.

Hi @josh-square,
Thank you for your response. Is it possible to cancel a transaction that has already been paid for using a transit IC card but hasn’t been completed because a customer doesn’t press “Continue” button? If so, is it possible to get a refund? We are using the Square POS SDK and app with self-checkout registers. Thank you.

They’ll need to return to Square POS to complete the transaction.

If the transaction was made (and your app did not get the completion callback because they exited early), you should still be able to refund these as you would any other Square POS transaction.

Thank you, understood

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