Default Theme Editor not working properly for Checkout error messages

Shopify Discussion

Topic summary

A Swedish company using Shopify Basic has implemented a workaround to enforce local pickup for installation help: they add a product with a shipping label that has no rates, triggering checkout error messages when customers attempt delivery.

The Issue:
They customized two error messages via “Edit default theme content” (locale files) to explain the installation help product restriction:

  • “Checkout shipping errors shipping method not available generic → One”
  • “Checkout payment errors → Order total changed”

Both edits appear correctly in the locale JSON, but only one message displays the custom text at checkout—the other shows the default message instead.

Current Status:
One commenter incorrectly suggested this requires Shopify Plus and Checkout Extensibility. The original poster clarified they’re only editing locale files (not checkout.liquid), which should work on Basic plan since one message already functions correctly.

The root cause of why one customized error message works while the other doesn’t remains unresolved.

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

I work (technically I’m doing a form of vocational training) in a Swedish company that refurbishes and sells old computers. We want to offer the customer help with getting everything installed, but to do that they have to choose local pickup. Since we only have Shopify Basic we have very limited access to the Checkout page, so we have solved this by giving the option in the Cart to add a “Help with intallation” Product that has a Shipping label without shipping rates attached. This way they can’t accidentally choose delivery if they have added said product since Shopify will just return an error message when trying to find shipping rates. And, if they still try to proceed with the purchase, they get yet another error message about the total sum of the order having changed.

The problem lies in said error messages; we would like them to include information about the “Help with installation” product being a possible cause for the error. I have identified them in the Default Theme Editor as “Checkout shipping errors shipping method not available generic → One” and “Checkout payment errors → Order total changed”, and edited them there. However, for some reason only the first one seems to work. I have checked the Locale file (sv.json as we only use Swedish for the store) and both changes are there, as seen below (the messages are in Swedish but you don’t need to understand them to see that they’re there):

  "shopify": {
    "checkout": {
      "payment_errors": {
        "order_total_changed": "Din orders totalsumma har ändrats.  Ifall du lagt till ”Installationshjälp” kan ordern inte levereras med post, välj istället ”Hämtning i butik”. I annat fall, granska uppgifterna och försök igen."
      },
      "shipping_errors": {
        "shipping_method_not_available_generic": {
          "one": "Din order kan inte levereras till vald adress.  Köper du ”Installationshjälp” fungerar endast valet ”Hämtning i butik”. I annat fall, kontrollera att adressen är korrekt och försök sedan igen, alternativt använd en annan adress."
        }
      }
    }
  }

As you can see in the picture below, only one of them actually seems to work.

Shopify-Checkout-Error-Messages-Problem.png
Shopify-Checkout-Error-Messages-Problem.png1139×812 42 KB

Do any of you have any idea what the problem could be?

2

Changing Checkout Page using Shopify Basic plan is currently impossible. For you to be able to change the Checkout Page, you need to be on Shopify Plus plan and utilize Checkout Extensibility.

Checkout.liquid had been deprecated as per August 13, 2024.

3

Thanks for replying! However, I think you misunderstand what it is I’m trying to do. I’m not doing anything that should require either editing Checkout.liquid or making use of Checkout Extensibility. I’m just changing two error messages that can be accessed via “Edit default theme content”*. From my understanding this just alters the Locale files, which shouldn’t pose any problems with a Basic plan. In fact, as I explained it does work for one of the messages.

*I now see that I mixed up some terminology in my original post and referred to this as the Default theme editor. I apologize if this caused any confusion.