Azure Functions
An Azure service that provides an event-driven serverless compute platform.
5,709 questions
Website issues occur in flex consumption plan with virtual network integration
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Chaya
5
Reputation points
What we want to achieve
In Azure Functions (flex consumption plan), we want to open the Functions website (https://{Functions Name}.azurewebsites.net) in the state that virtual network integration is configured.
■ Event
When opening the Functions website, a screen with the text “The service is unavailable” is displayed.
However, when the virtual network integration is disconnected, a normal screen is displayed.
■Error Messages
◆Open the Troubleshooting Tools > Diagnostic Tools > Network/Connectivity Troubleshooter and select Connectivity issues, and you will see the following error message for virtual network integration. The following error occurs for virtual network integration.
▼ Error message
VNet integration is not healthy
◆Open the Troubleshooting Tools > Diagnostic Tools > Network/Connectivity Troubleshooter and select Configuration issues. The following error occurs for virtual network integration.
▼ Error message
Subnet 'snet-03' is not valid for integration with App '{Functions Name}'
Subnet snet-03 is owned by App Service Plan undefined and cannot be used for Regional VNet integration by App Service Plan asp-02 which hosts the app { Functions Name}.
*asp-02 is an App Service Plan created at the same time when Functions are created.
◆The configuration screen for virtual network integration in Functions is as follows.
◆The setting values for the subnets subject to virtual network integration are as follows.
■Reference Information
{count} vote
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Andriy Bilous 11,731 Reputation points MVP2025-03-29T08:01:38.63+00:00 Hello Chaya
There could be multiple reason of the described error:
What I see from your screenshots:Subnet Delegation Issue:
- The error means that the subnet
snet-03is owned by an undefined App Service Plan and cannot be used for Regional VNet integration by the App Service Planasp-02. - Subnet delegation must be explicitly set to
Microsoft.Web/serverFarmsfor App Service Plan integration.
Flex Consumption Plan Limitations:
- The Flex Consumption Plan has specific requirements for VNet integration, including the need for proper subnet delegation and resource provider registration.
Each subnet used for Regional VNet Integration in Azure App Service can only be associated with one App Service Plan. You're trying to use a subnet (
snet-03) that's already associated with another (possibly deleted or undefined) App Service Plan. Azure still considers it "owned" by that previous plan. Remove Subnet Delegation manuallyhttps://learn.microsoft.com/en-us/azure/app-service/overview-vnet-integration#requirements
- The error means that the subnet
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Chaya 5 Reputation points
2025-03-31T02:39:35.74+00:00 delete
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Chaya 5 Reputation points
2025-03-31T02:42:13.57+00:00 delete
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Chaya 5 Reputation points
2025-03-31T03:39:38.2266667+00:00 delete
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Chaya 5 Reputation points
2025-03-31T04:51:56.39+00:00 Hello Andriy, Thank you for your response. I have a few clarifications regarding the subnet delegation issue:
- I noticed that the documentation mentions setting the subnet delegation to Microsoft.App/environments instead of Microsoft.Web/serverFarms. Is my understanding correct on this point?
https://learn.microsoft.com/en-us/azure/azure-functions/flex-consumption-plan#considerations
- I am aware that the Flex Consumption Plan cannot coexist with other VNet integrations.
Just to confirm, I deleted the subnet and set up a new VNet integration, but I still received the same error message.
I appreciate your assistance in resolving this issue.
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Ranashekar Guda 1,265 Reputation points Microsoft External Staff2025-04-04T09:32:12.4566667+00:00 Hi @Andriy Bilous,
Could you please share your suggestions on @Chaya queries?
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Nicholas Wanberg 0 Reputation points2025-04-04T10:36:11.99+00:00 I don't know the cause of the problem either, but the configuration issue you're discussing is misleading. The configuration troubleshooter is meant to assess the health of a subnet before you connect to it, not after it's already configured. In this case, that's the error you get from connecting to the subnet and then checking the configuration of the subnet you're already connected to. I'm researching the same problem, and if I disconnect from the vnet and try the configuration on the same subnet, it will say that it is valid:
If you go ahead and reconnect and try again, you'll again get:
It's "invalid" only because something is already connected to it (I.e. the current app service plan).
You also cannot set a Flex plan's subnet to Microsoft.Web/serverFarms. Attempting to do so will produce an error and the subnet configuration will fail to save the change. Microsoft.App/environments is mandatory.
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Nicholas Wanberg 0 Reputation points
2025-04-04T15:22:08.5066667+00:00 I looked through the configurations on a similar problem. I don't know if this is your solution or not, but:
A. Confirm that you're actually unable to access the private endpoint in code.
B. Note that using @Microsoft.KeyVault functionality in Azure Function environment variables does not respect vNet integration functionality (at least in flex consumption apps. I have not tried in premium).
C. Understand that the errors you're seeing are essentially meaningless. My vNet integration works fine, and I get the same feedback from the troubleshooter.
I hope this helped!
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Ranashekar Guda 1,265 Reputation points Microsoft External Staff
2025-04-07T11:12:35.7433333+00:00 Hi @Chaya,
Just checking in to see if the below answer provided by @Nicholas Wanberg helped. -
Ranashekar Guda 1,265 Reputation points Microsoft External Staff
2025-04-08T10:27:41.22+00:00 Hi @Chaya,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet.
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