Failed to create App Service Managed Certificate

@Jim Jackson you for providing the Activity Log details. The error confirms the cause:

Properties.CanonicalName is invalid. Found a duplicate certificate ... available or in pending issued

Azure already has a certificate operation for transfer.sundance-inc.net associated with the same App Service Plan, and the pending operation has ID 702773d2-3b86-4a2d-a98d-32d7dbf25269.

This prevents Azure App Service from creating another managed certificate for the same hostname while the existing operation is still pending.

I recommend:

1. Go to App Service → TLS/SSL settings → Private Key Certificates (Managed) and check whether a certificate for this hostname already exists in Pending or Failed state.
2. If an existing pending/failed certificate is present, remove it and allow some time for the backend state to clear.
3. If the certificate operation is no longer visible in the portal, wait until the pending operation reaches its timeout shown in the Activity Log, then retry the certificate creation.
4. If the operation remains stuck after the timeout, open an Azure Support request and provide the Pending certificate operation ID from the Activity Log so the App Service team can investigate the backend state.

This is a known pattern with App Service Managed Certificates when another certificate operation for the same hostname is already available or pending.

Since Azure is already reporting the hostname as eligible, I would focus on clearing the duplicate/pending certificate operation rather than changing the DNS configuration.

Reference: Troubleshoot Azure App Service certificates

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