Question: .NET 6 In-Process Function runs fine on Azure .NET 8 Isolated ?!

[Chrissie]

What version of .NET does your existing project use?

.NET 6

What version of .NET are you attempting to target?

.NET 8

Description

If I build an Azure Function with the In-Process model, on .NET 6, I am able to run it on .NET 8 Isolated in Azure.
I don't understand why this works, I thought the Isolated-Worker would not accept existing In-Process Functions?
Can someone explain why this works? I can't find any source or reference which states that this should work.

Steps:

• Have an existing Azure Function on Azure
• Create an empty Azure Function, In-Process, .NET 6.0, Http Trigger in Visual Studio
• run dotnet publish -o Publish
• Zip deploy using Azure CLI az functionapp deployment source config-zip
• Make sure the Azure Function App Configuration has FUNCTIONS_WORKER_RUNTIME with value dotnet-isolated. If not, change it.

Project configuration and dependencies

• Empty .NET 6 In-Process Azure Function Project with HttpTrigger
• .csproj:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <AzureFunctionsVersion>v4</AzureFunctionsVersion>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="4.4.0" />
  </ItemGroup>
  <ItemGroup>
    <None Update="host.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <CopyToPublishDirectory>Never</CopyToPublishDirectory>
    </None>
  </ItemGroup>
</Project>

• Azure
  

Link to a repository that reproduces the issue

No response

[cjaliaga]

Explained as part of this PR in the section Why it works in 4.34 . This behavior will be removed in the future.

[satvu]

Closing as answered.