Web App: Migration Between Subscriptions in Different Entra Tenants — Name Reservation Issue

Question

Web App: Migration Between Subscriptions in Different Entra Tenants — Name Reservation Issue

LKMaryWill-5007 0

Problem description

I am trying to migrate a production web app (Web App on Windows) from one subscription in a different Entra tenant to another. After deleting the web app, I attempted to recreate it with the same name in the new subscription, but I received an error stating that the hostname 'gravitysync' already exists. I want to understand if there is a reservation or hold on this hostname and how long it typically lasts.

Environment

Azure Web App (Windows), moving resources between subscriptions in different Entra tenants.

What I've already tried

I reviewed the case details and diagnostic information provided. I have not attempted to recreate the web app in a different subscription within the same tenant, as I only have access to one subscription in the source tenant. I confirmed that within the tenant, I can recreate the app with the same name after deletion.

Current status

I am seeking guidance on whether the hostname reservation can be released, the typical duration of such reservations, and supported methods to expedite the release, to successfully recreate the web app with the same name in the new subscription.

Will Henderson 0 Reputation points

2026-10-25T09:35:00.7133333+00:00

Support's step 1 and 2 checks are done. gravitysync still shows as a recoverable deleted app in the source subscription (35ccc46f-…).

Deleted site ID Deleted at (UTC) Resource group

44371829 2026-10-24 18:56:55 GravitySQL

44371830 2026-10-24 18:56:57 GravitySQL

44371832 2026-10-24 18:56:58 GravitySQL

The list has three entries because the deletion appears to have been recorded more than once. Different calls returned two or three of them. All three share the delete time from the activity log, within seconds of 18:56:44.

What this means

• Most likely cause: the deleted-app record keeps the name reserved for the original subscription, as Support's point 3 describes. Azure's subdomain-takeover protection also fits.

• No early release from me: the CLI I used can list deleted apps and restore them, but it has no purge command. I couldn't find a supported way to purge the records early, so I haven't tried to bypass the hold.

• Rollback is available: I can restore the old app from these records, which would bring production back in the source subscription quickly. Restoring gives the name back to the source tenant, so I'll only do it if you ask.

2 answers

Your answer

Will Henderson 0 Reputation points

2026-10-25T09:35:00.7133333+00:00

Support's step 1 and 2 checks are done. gravitysync still shows as a recoverable deleted app in the source subscription (35ccc46f-…).

Deleted site ID Deleted at (UTC) Resource group

44371829 2026-10-24 18:56:55 GravitySQL

44371830 2026-10-24 18:56:57 GravitySQL

44371832 2026-10-24 18:56:58 GravitySQL

The list has three entries because the deletion appears to have been recorded more than once. Different calls returned two or three of them. All three share the delete time from the activity log, within seconds of 18:56:44.

What this means

• Most likely cause: the deleted-app record keeps the name reserved for the original subscription, as Support's point 3 describes. Azure's subdomain-takeover protection also fits.

• No early release from me: the CLI I used can list deleted apps and restore them, but it has no purge command. I couldn't find a supported way to purge the records early, so I haven't tried to bypass the hold.

• Rollback is available: I can restore the old app from these records, which would bring production back in the source subscription quickly. Restoring gives the name back to the source tenant, so I'll only do it if you ask.

Answer 1

Hi LKMaryWill-5007 & thx for join me at Q&A platform,

what u're seeing is actually expected behavior with Azure App Service, and the fact that you can recreate gravitysync in the original tenant is a pretty good indication of what's happening. Azure App Service has a built-in name reservation mechanism designed to prevent subdomain takeovers. When a web app is deleted, its *.azurewebsites.net hostname isn't immediately released for use by subscriptions belonging to a different Microsoft Entra tenant.

Subscriptions within the original tenant can generally reuse the name during the reservation period. Subscriptions in another tenant cannot, even when the original web app has been completely deleted. So this isn't necessarily a leftover resource or a problem with your target subscription.

Regarding the cooldown period, Microsoft moderators have previously indicated that it depends on the original subscription's quota ID. They've cited approximately 7 days for some subscription types and up to 180 days for Enterprise/CSP subscriptions.

I wouldn't treat either duration as a guaranteed release date, tho. The exact reservation status and expiry need to be confirmed by Microsoft. There's no supported Azure CLI or PowerShell command that lets you manually release this reservation across tenants. Deleting the resource group, removing DNS records, or retrying deployment won't bypass the protection.

For a production migration, I'd open an Azure App Service support case and specifically request an early release of the deleted web app's hostname reservation for cross-tenant reuse. Provide the original app name, source and destination subscription IDs, both tenant IDs, original resource group, Azure region, and approximate deletion timestamp. Support can investigate the reservation and determine whether a backend release is possible after verifying ownership. There have been cases where Microsoft successfully released these reservations, but it's not an automatic or guaranteed operation.

If the migration is urgent, the practical alternative is to create the destination web app under a different name and configure your existing custom domain against it. That avoids waiting for gravitysync.azurewebsites.net to become available, although any dependencies on the original default hostname would still need to be addressed.

Also, keep in mind that the deleted web app's restore retention period and the hostname reservation cooldown are separate mechanisms. Restoring a deleted app doesn't automatically transfer its name to another tenant.

My recommendation is not to wait for an assumed 7-day or 30-day expiry if this is production-critical. Get App Service Support to check the actual reservation and whether an early release is possible.

rgds,

Alex

p.s. if my answer is help - pls mark it as an answer

Answer 2

Hello,

Welcome to the Microsoft Azure Community.

Good evening, @LKMaryWill-5007 . Thank you for reaching out and providing details about your scenario. This behavior may be related to the temporary retention of the name by Azure App Service following its deletion—especially since the new subscription belongs to a different tenant.

I suggest the following checks:

1. Confirm the deletion: In the Azure portal, navigate to "App Services" and look for the Manage Deleted Apps option within the original subscription. Check whether the gravitysync app still appears as deleted.

2. Check via PowerShell: Run Get-AzDeletedWebApp within the context of the original subscription to see if the app remains recoverable and to identify the date it was deleted.

3. Check the timeframe: Deleted apps can remain recoverable for up to 30 days. This period does not, in itself, guarantee that the name will be automatically released for use by another tenant. Please refer to the official documentation on recovering deleted apps.

4. If the name remains unavailable: Open a support ticket with Azure Support. Provide the name gravitysync, the date of deletion, the tenants involved, and the full error message. Request an investigation into the reservation and inquire about the possibility of an early release.

Important: Azure documentation confirms that the DNS names of deleted apps are protected against reuse by other tenants. There is no guarantee that the name will be released immediately through standard actions in the portal.

As an alternative, you could temporarily create the app using a different name and migrate your custom domain, if applicable.

Technical reference documentation