Completing online orders at POS with custom payment

Retail & Point of Sale

Topic summary

A user encountered an error when attempting to complete online orders at the point of sale using the custom payment option. Despite custom payments supposedly not being processed by Shopify, the system returned a “Payment declined” error message.

Key findings:

  • Custom payment works fine for regular POS orders
  • The issue only occurs when processing online orders through the POS app
  • Other payment methods (like cash) work without problems for online orders

Resolution:
Shopify Retail Support confirmed that completing online orders in-store using custom payment is not supported in Shopify POS or POS Pro.

Workaround:
The user found a third-party app called “Sales Terminal POS” that enables editing online orders and accepting custom payment methods in-store.

Community reaction:
Another participant expressed frustration that Shopify promotes manual payment methods and in-store pickup for online orders but lacks native functionality to process these transactions through their own POS system.

Summarized with AI on November 2. AI used: claude-sonnet-4-5-20250929.
1

I’m trying to collect payment for an online order using the custom payment button on the POS app. However, whenever I try it, I get the screen which says it will “Order will be marked as paid. Custom payments are not processed by Shopify.” and when I click “Mark as Paid”, the screen starts to process and then I get

“Payment declined”
There was an issue with Shopify and the payment couldn’t be processed"

Why is this happening? I though custom payment is not being processed by Shopify. Why is the payment being declined?

If I select a different payment method (ie Cash) it works fine and allows me to enter the amount paid and marks as paid.

Have I forgotten to set up something? Why is Custom Payment not working?

I can checkout a POS order using the custom payment without a problem. The problem only happens when I try to complete an online order using the POS app.

2

I"m going to answer my own question. Talked with Shopify Retail Support. This functionality (finishing up online orders in store using custom payment) is not supported by Shopify POS (or POS Pro).

I’ve found an App called Sales Terminal POS which WILL allow me to edit online orders and use custom payment method.

2 Likes
3

It ridiculous that Shopify advertises the possibility to create manual payment methods online and offer in-store pickup, but doesn’t offer a clean way to process orders in-store for online orders using their own Shopify POS.