App embed extension blocks URL throwing 404

Shopify Apps

Topic summary

Issue: App embed extensions are failing to load due to CDN URLs returning 404 errors. The problem affects multiple merchants and partners across production environments.

Timeline & Scope:

  • Started occurring on February 28th evening
  • Multiple developers confirmed experiencing identical behavior
  • Issue appears related to how Shopify handles theme app extensions uploaded before CLI version ~3.48

Root Cause:

  • CDN URLs are serving incorrect version numbers in the path
  • Affects extensions deployed with older Shopify CLI versions

Workaround (from ScalaApps):

  • Redeploy the theme app extension using Shopify CLI version 3.48.0 or later
  • Recommended: Use CLI version 3.49.7 specifically
  • After redeployment, Shopify will serve the correct CDN link automatically
  • Note: If you don’t have the last deployed version of your code, you’ll need to wait for Shopify’s solution

Resolution:

  • Shopify acknowledged the issue via email on February 27th (after initial report on February 25th)
  • GitHub issue tracking: https://github.com/Shopify/cli/issues/3488
  • Shopify confirmed they’ve identified and fixed the issue on their end
  • No manual fixes required from partners or merchants
Summarized with AI on November 11. AI used: claude-sonnet-4-5-20250929.
1

Expected behavior: When merchant adds app embed block, expected link to load app embed assets is throwing 404. This results into app embed block not loading.

Old URL: https://cdn.shopify.com/extensions/3415078e-1e03-44d0-a5eb-807108d6533a/1.3.0/assets/ef-faq-plus-script.min.js (Works)
New URL: https://cdn.shopify.com/extensions/3415078e-1e03-44d0-a5eb-807108d6533a/helplab-faq-page-product-faqs-0/assets/ef-faq-plus-script.min.js (throws 404)

Timeframe: This started happening yesterday (Feb 28th) evening. Other partners are also facing similar issues as per attached screenshot.

Environment: Production for multiple merchants.

Other partners: https://ibb.co/5TbGSpf

2 Likes
2

Experiencing the exact same behaviour.

It really needs Shopify Dev’s attention. Frustrating to see this breaking our store.

3

Same issue is happening with us as well. On some stores the shopify CDN url has a different version number, which is leading to 404 errors.

1 Like
4

We started seeing this as well. Identical behavior to what you describe.

1 Like
5

I communicated this bug to Shopify on the 25th of February, I messaged them everywhere (facebook,slack, discord, github, twitter,email).

They still haven’t provide a solution, only yesterday did they recognized the issue through email.

You can check the github issue here where I explain in detail, the problem seems related to how Shopify is dealing with theme app extensions that have been uploaded before shopify cli version ~3.48:
https://github.com/Shopify/cli/issues/3488

How to fix it:

The way to fix it is just to deploy the exact same code you used in theme app extension but using any version after 3.48.0,

I personally use “@shopify/app”: “3.49.7”, because it doesn’t force you to start a graphiql server.

After you deploy the code, Shopify will serve the right link for your app (the CDN link will include “your-app-name-1” instead of “your-app-name-0”).

If you don’t have the last version that you deployed of your code, you’ll need to wait for them to provide a solution, I gave up after 24 hours because the last bug that I reported was around a year ago and they never even said anything about it.

6

Shopify responded back with message saying that they’ve identified and fixed this issue on their end so there won’t be any manual fixes needed on partner or merchants end.

2 Likes