Azure Static Web Apps custom domain intermittently returns 404 after resource recreation

Sjoerd Buurman 0 Reputation points
2026-08-24T05:58:32.73+00:00

I deleted and recreated an Azure Static Web App in West Europe, reusing the same resource name and custom domain.

The autogenerated Azure hostname works consistently, but the custom domain intermittently returns the generic “Azure Static Web Apps - 404: Not found” page.

Environment:

  • Region: West Europe
  • Plan: Free
  • Custom domain: [www.syncbx.com]
  • Azure hostname: zealous-cliff-030012203.7.azurestaticapps.net
  • Custom domain status in Azure: Ready
  • DNS: CNAME correctly points to the Azure hostname

Observed behavior:

  • 7 page refreshes: 5 returned HTTP 200 and 2 returned HTTP 404.
  • Across 29 requests to the custom domain, 19 returned 200 and 10 returned 404.
  • Existing CSS, JavaScript and image files also randomly return 404 within otherwise successful page loads.
  • All requests use the same Azure IP and HTTP/2 connection.
  • Requests bypass browser cache and are not handled by a service worker.
  • The 404 response is Azure’s generic 2,400-byte Static Web Apps error page.
  • Live tests showed mixed 200/404 responses on the custom domain, while the autogenerated hostname returned 200 consistently.

Timeline:

  • Static Web App deletion started: 2026-08-23 12:08 UTC
  • Recreated with the same resource name: 2026-08-23 12:09 UTC
  • Custom domain added again: 2026-08-23 12:20 UTC
  • Custom domain reported Ready: 2026-08-23 12:51 UTC

This strongly suggests a stale or partially propagated custom-domain/backend mapping after resource recreation.

This appears identical to: https://github.com/Azure/static-web-apps/issues/1785

Can Microsoft verify and purge or resynchronize the backend hostname mapping? Is there a supported procedure or expected propagation period after recreating a Static Web App with the same custom domain?

Azure Static Web Apps
Azure Static Web Apps

An Azure service that provides streamlined full-stack web app development.

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  1. kagiyama yutaka 5,165 Reputation points
    2026-08-24T21:03:32.2266667+00:00

    I think the user‑side resync step is removing the custom domain and adding it back, and checking the CNAME points to the new Static Web App hostname. And when 404s still show up after that and the domain is marked Ready, the rest is handled by Microsoft support.

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  2. Shailesh Ganesh Shripati 190 Reputation points
    2026-08-24T17:59:45.4266667+00:00

    Kindly remove and re-add the custom domain on the new Static Web App. This often clears any stale bindings and triggers a fresh propagation across Azure's edge network.

    Steps to follow:

    Go to the Azure Portal > Your new Static Web App >Custom domains.

    Select and remove the affected custom domain.

    Click Add > Choose Custom domain on other DNS (or the appropriate option) > Enter your domain and complete the validation (usually via TXT record).

    Once validation shows as successful, wait 15–30 minutes for edge propagation, then test thoroughly.

    If the intermittent 404s continue after re-validation and waiting ~2 hour, please reply with your Subscription ID, the name of the new Static Web App, and a screenshot of the Custom domains blade to provide to MS Support team

    Reference Documents :

    https://learn.microsoft.com/en-us/azure/static-web-apps/custom-domain

    https://learn.microsoft.com/en-us/troubleshoot/azure/app-service/connection-issues-with-ssl-or-tls/troubleshoot-custom-domain-issues-azure-app-service

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