Customer Account UI Extension page fails to load — "There's a problem loading this page," Shopify's own frontend blocks a cross-origin SVG sprite

Extensions
1

Hi Dev Community,

I have a customer-account.page.render extension (allow_direct_linking = true) that consistently fails to load via its real production URL, showing Shopify’s generic “There’s a problem loading this page / Check the URL or try again in a few minutes” error — for every visitor, every browser, regardless of account.

Store uses a custom account domain: account.newfriendscoffee.com

Console error, repeats on every load attempt:
Unsafe attempt to load URL https://cdn.shopify.com/shopifycloud/customer-account-web/production/sprite-1b2b2c.svg
from frame with URL https://account.newfriendscoffee.com/pages/.
Domains, protocols and ports must match.
Network tab confirms this request as (blocked:origin). This is Shopify’s own customer-account-web frontend failing to load its own icon sprite asset via a cross-origin SVG reference — not a request my extension code makes.

What I’ve ruled out:

  • My own extension/backend code (reverted to a previous app version — identical failure)
  • Browser/session (Chrome + Edge, two different customer accounts)
  • Stale registration (full app uninstall + reinstall — confirmed a brand-new CustomerAccountPage resource ID was generated, identical failure persists)
  • Backend/OAuth state (my app’s logs confirm a valid session exists and OAuth completes cleanly both before and after reinstall — but zero requests from this extension ever reach my backend at all, meaning the failure happens before my app is contacted)
  • Tunnel/VPN networking (fully disabled, confirmed stable, identical failure)
  • Customer accounts config (“New customer accounts” confirmed active, not Classic)
  • Extension deployment (confirmed via the Dev Dashboard that the extension is correctly registered, active, and healthy in the current app version — structurally identical to a sibling extension that works fine elsewhere)

One clue I think is relevant: this extension has worked correctly when tested via the Shopify CLI’s Dev Console preview link during development — this may be the first time it’s been loaded via its actual production URL on this store’s custom account domain, so this could be specific to serving a customer-account.page.render extension through a custom account domain rather than the default .myshopify.com-style one.

Has anyone else seen this specific sprite-1b2b2c.svg cross-origin block on a custom account domain, or know a workaround?

Cheers
JK

2

Morning,

Update: reproduced this identically on a second, completely separate store — a vanilla dev store (your-palate-picker-dev.myshopify.com) with no custom account domain (uses the default shopify.com/108143182169/account/… format). Same extension, same exact console error:

Unsafe attempt to load URL https://cdn.shopify.com/shopifycloud/customer-account-web/production/sprite-1b2b2c.svg from frame with URL https://shopify.com/108143182169/account/pages/01a09254-7f94-7db3-a69f-37e78f89ff9b.
Domains, protocols and ports must match.

This rules out the custom-account-domain theory entirely — it’s not specific to my store’s domain setup.

The one common factor across both failures: this is a customer-account.page.render extension’s real, non-preview production URL in both cases.

It has only ever worked for me via the Shopify CLI’s Dev Console preview link (which uses a profile_preview_token-based preview URL) — the real customer-facing URL fails identically on every store I’ve tried it on.

Cheers
JK

3

Hi there!

I’m also experiencing the exact same issue with a nearly identical setup; however, I haven’t pinned it down to the CORS error (yet). I’d somehow assume that if Shopify broke all custom extension pages, they would’ve noticed by now so I’m still assuming there might be a different problem with my particular setup.

So far you’ve done way more testing and narrowing than I did, so I cannot contribute anymore than seconding your request. However, I’ll dig in some different directions and provide an update in case I find anything useful.

Regards,
D

5

@jkuknfc No idea why your posts got flagged, but I can confirm that the CORS did not turn out to be the cause of my customer account page not rendering. Instead, the issue was that the app page had not been added as an actual customer accounts page yet (I assumed it would be enough to link to it via the menu).

Shopify’s docs do a terrible job at making it clear how their bloated architecture should be handled.

I can’t tell whether it’s the same issue for you, but I can confirm that the CORS error has nothing to do with the app failing.