Unable to associate public ip with application gateway

Hello Sean Owen,

Thanks for raising this question in Q&A forum.

I understand you are unable to associate an existing Public IP (IP A), previously used by a VM, with a new Application Gateway, and you need to retain this specific IP to avoid updating DNS records for your customers.

This issue is almost always caused by a SKU Mismatch between the Public IP address and the Application Gateway.

Here is the likely scenario and solution:

1. SKU Requirement:
   • Application Gateway V2 (Standard_v2 or WAF_v2) requires a Standard SKU Public IP. It cannot use a Basic SKU IP.
   • Application Gateway V1 (Deprecated) could use Basic SKU IPs.
2. Your IP's SKU:
   • Since "IP A" was previously attached to a VM, it is possible (and common for older deployments) that "IP A" is a Basic SKU Public IP.
   • If you are trying to create a modern Application Gateway (V2), it will reject the Basic IP.

How to Verify and Fix:

• Check IP SKU: Go to the Azure Portal > Search for "Public IP addresses" > Click on "IP A". Look at the "SKU" field in the Overview blade.
  • If it says Basic: You cannot attach it to an App Gateway V2 directly.
• The Solution (Upgrade IP):
  • You can upgrade a Basic Public IP to Standard in-place without losing the IP address.
  • Go to the Public IP resource ("IP A") in the portal.
  • Look for a banner or an option in the menu to "Upgrade to Standard SKU". (Note: The IP must be disassociated from all resources first, which you said you have already done).
  • Once upgraded to Standard, you should be able to select it during the Application Gateway V2 creation.
• Alternative (Dynamic vs. Static):
  • Ensure the Allocation Method is Static. App Gateway V2 requires Static IPs. (Standard SKU IPs are always Static, so upgrading fixes this too).

If "IP A" is already Standard SKU and it still fails, ensure it is in the exact same region as the Application Gateway you are creating.

If helps, approve the answer.

Best Regards,

Jerald Felix

This usually happens when the public IP does not meet the requirements for Application Gateway.

A gateway can only accept a public IP that is Standard SKU, Static, in the same region, and fully detached from every resource.

So check the following on IP-A:

SKU must be Standard. If it is Basic, it cannot be used for an Application Gateway and cannot be upgraded. Only Microsoft support can help you keep the same IP.

IP must be Static.

Region must match the Application Gateway region.

The IP must not be linked anywhere (VM NIC, load balancer, old gateway, etc.). Sometimes a “ghost” association remains, and support must remove it.

If all requirements look correct and the portal still blocks it, open a support ticket and ask them to clear the hidden association or convert the IP so you can reuse the same address without forcing customers to update DNS.

@Jerald Felix @Ravi Varma Mudduluru @Ravi Varma Mudduluru @Adam Zachary

Hi, thanks for your responses.

1. The IP is standard sku.
2. The IP is static.
3. There are no other resources showing as attached to this IP.
4. Running the powershell command provided, IpConfiguration came back empty.

Please see attached image for reference, it shows the ip is static, standard sku and ipconfig is empty.