Help! Custom Domain Suddenly Stopped Working on Hydrogen – 404 Error (May 7, 2025)

Technical Q&A

Topic summary

A Hydrogen-built Shopify store suddenly began returning 404 errors on its custom domain (theblindboxfactory.com and www variant) starting May 7, 2025. The site continues to function normally when accessed via the default Oxygen preview URL, suggesting a domain connection issue rather than a build problem.

Key troubleshooting steps recommended:

  • Verify domain connection status in Shopify admin (Settings > Domains) and check for SSL certificate issues
  • Confirm DNS records are correct:
    • A record for [email removed] pointing to 23.227.38.65
    • CNAME for www pointing to shops.myshopify.com
  • Ensure custom domain is properly added and verified in the Oxygen dashboard
  • Set a primary domain (www or non-www) to avoid version conflicts
  • Allow up to 48 hours for DNS propagation if recent changes were made

The issue remains unresolved. If standard checks fail, removing and re-adding the domain in both Shopify and Oxygen may reset the connection.

Summarized with AI on October 28. AI used: claude-sonnet-4-5-20250929.
1

Hi everyone,

I’m reaching out to see if anyone has experienced a similar issue or might have a solution.

Our Hydrogen-built Shopify site was working perfectly with our main domain theblindboxfactory.com, and also with www.theblindboxfactory.com. However, since Wednesday, May 7, both versions of the domain have started returning a 404 error.

Screenshot 2025-05-10 145925.png
Screenshot 2025-05-10 145925.png1288×708 17.2 KB

What’s strange is that the site still works when we set the primary domain to the default Hydrogen preview link:
https://the-blindbox-factory-496cf34d6e65094d0ab4.o2.myshopify.dev/

We haven’t made any changes on our end. This was only brought to our attention when my employee reported the issue. We’ve reached out to Shopify customer support, tried adding additional DNS settings (A records and CNAME), but nothing has fixed it so far. But I am confident that the problem is on the domain setup mainly because it runs on https://the-blindbox-factory-496cf34d6e65094d0ab4.o2.myshopify.dev/ if i set it to primary. While it won’t work on theblindboxfactory.com.

I’m open to trying any recommendations or troubleshooting steps you can share. If you’ve encountered this before or have any insights, I’d truly appreciate the help!

Thanks in advance,
Chris

1 Like
2

Hi Chris,

It definitely sounds like a domain connection issue, not a problem with your Hydrogen build. If the site works on your Oxygen preview link but not on your custom domain, here are the main things to check:

  1. Domain status in Shopify admin
    Go to Settings > Domains and confirm that both theblindboxfactory.com and www.theblindboxfactory.com are listed and marked as “Connected.” If either shows “Not connected” or “SSL pending,” that’s likely the issue.

  2. DNS settings
    Double-check your domain’s DNS settings:

  • The A record for @ should point to 23.227.38.65

  • The CNAME record for www should point to shops.myshopify.com
    Also make sure there are no extra A or AAAA records that might conflict with Shopify’s setup.

  1. Oxygen setup
    If you’re deploying to Oxygen, make sure your custom domain is properly added and verified in the Oxygen dashboard for your Hydrogen app. Even if DNS is correct, the domain won’t work unless it’s linked to your storefront there.

  2. SSL certificate
    Sometimes an issue with the SSL certificate can cause a 404. In your Shopify admin, check that the SSL certificate for your domain is active. If it’s stuck on “Pending,” that can block access.

  3. Primary domain setting
    Set either the www or non-www version as your primary domain and redirect all traffic to it. This helps avoid conflicts between versions.

  4. DNS propagation
    If you’ve made changes recently, it might just be a matter of time. DNS changes can take up to 48 hours to fully propagate.

If you’ve confirmed all of the above and it’s still returning a 404, try removing and re-adding the domain in both Shopify and the Hydrogen/Oxygen project to reset the connection.