Adding custom domain to Static Web App but vaildation never completes

Question

Adding custom domain to Static Web App but vaildation never completes

Jim Matson 0

I have a static web app. I try to add a custom domain but validation never completes. After a couple of days it comes back and says it failed. When I view the details it says "An unknown error has occurred while adding your custom domain. Please try again later." However you are not able to generate a new code. Deleting the entry in Custom Domains and recreating with a new code still does not validate. My domain DNS is in M365. If it would validate I could add the CNAME to M365.
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Praneeth Maddali 7,315 Reputation points Microsoft External Staff Moderator

2026-04-01T01:27:54.61+00:00
Hi @Jim Matson

Thanks for reaching us regarding your issue and sharing the details and the screenshot

The “An unknown error has occurred while adding your custom domain” along with validation never completing is a common issue on Azure Static Web Apps, especially when DNS is hosted in Microsoft 365. In most cases, it’s caused by one (or both) of these:

The TXT ownership record needing the _dnsauth prefix

A missing or restrictive CAA record that blocks DigiCert (the certificate authority Azure uses)

Recommended Steps (Try in this order):

Delete the failed entry Go to your Static Web App > Custom domains, delete the stuck devsite entry, and wait 5–10 minutes.

Re-add the domain & generate token Add the custom domain again and click Generate code to get a fresh TXT token.

Add the TXT record in Microsoft 365 (important)

Type: TXT

Name / Host: _dnsauth.devsite

Value: Paste the exact token from Azure

TTL: Default is fine

Add/Update the CAA record (often the hidden cause)

Type: CAA

Name / Host: @

Flag: 0

Tag: issue

Value: digicert.com

Wait 15–60 minutes for DNS propagation, then refresh the Azure portal. Once it shows Validated, add the CNAME record (devsite → your app’s .azurestaticapps.net hostname).

Reference :

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

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

https://github.com/Azure/static-web-apps/issues/1447

If it still doesn’t validate after these steps, could you please share the full custom domain or screenshots of your current TXT and CAA records in M365? I’ll check the live DNS and give more targeted advice.

If the answer is helpful, Please do click "Accept the answer” and Yes, this can be beneficial to other community members.

If you have any other questions, let me know in the "comments" and I would be happy to help youll.
Praneeth Maddali 7,315 Reputation points Microsoft External Staff Moderator

2026-04-02T00:16:27.6466667+00:00

Hi @Jim Matson

Just following up to see if your issue has been resolved or if you had a chance to review my earlier comment?
Shree Hima Bindu Maganti 7,035 Reputation points Microsoft External Staff Moderator

2026-04-09T17:44:24.9066667+00:00

Hi @Jim Matson
Apology for the delay reply
When switching your domain to Azure DNS, the custom domain validation in Azure Static Web Apps will not complete until the DNS delegation is fully updated and propagated. You need to ensure that your domain’s nameservers at the registrar are pointing to the Azure DNS nameservers, because Azure will only validate against the authoritative DNS. After that, recreate the required TXT record (typically asuid.<yourdomain>) in your Azure DNS zone using the exact value generated in the portal, and verify it is publicly resolvable using tools like nslookup before retrying validation. If your domain is still partially using Microsoft 365 DNS (as suggested by existing records like Outlook/MX), Azure may not see the correct TXT record, causing validation to remain stuck. Once delegation and propagation are complete, the validation should succeed.
https://learn.microsoft.com/en-us/azure/static-web-apps/custom-domain
https://learn.microsoft.com/en-us/azure/dns/dns-delegate-domain-azure-dns
If you have any other questions, let me know in the "comments" .