Running dotnet-isolated AzureFunction Does Not Work

Overview

You have developed an Azure Function v4 with .NET 6.0 containing only HTTP-triggered functions. While everything works fine locally, deploying the function to Azure results in a 500 Status Code for any endpoint. The error thrown is:

InvalidOperationException at Microsoft.Azure.WebJobs.Script.Workers.Rpc.RpcFunctionInvocationDispatcherLoadBalancer.GetLanguageWorkerChannel: Did not find any initialized language workers

Application Settings

The current application settings in Azure are configured as follows:

Configuration Details:

• Operating System: Windows
• Runtime Version: 4.0.1.16815
• Location: West Europe

Project File Configuration

Below is the configuration of your project file (.csproj):

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <AzureFunctionsVersion>v4</AzureFunctionsVersion>
    <OutputType>Exe</OutputType>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="11.0.0" />
    <PackageReference Include="Microsoft.ApplicationInsights" Version="2.20.0" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.6.0" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.OpenApi" Version="1.0.0" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http" Version="3.0.13" />
    <PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.3.0" OutputItemType="Analyzer" />
  </ItemGroup>
  <ItemGroup>
    <None Update="host.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>
</Project>

Local Settings Configuration

Your local.settings.json file is configured as follows:

{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
    "StorageConnectionString": "UseDevelopmentStorage",
    "APPINSIGHTS_INSTRUMENTATIONKEY": "MyInstrumentationKey"
  },
  "Host": {
    "LocalHttpPort": 7071,
    "CORS": "*"
  }
}

Troubleshooting Steps

1. Ensure All Dependencies are Updated:
-> Ensure all the packages in your .csproj file are up-to-date.
2. Check Application Settings:
-> Verify that the FUNCTIONS_WORKER_RUNTIME is set to dotnet-isolated.
3. Deployment Issues:
-> Redeploy the function to ensure there were no issues during the deployment process.
-> Check the Azure portal logs for more detailed error information.
4. Function App Configuration:
-> Make sure that the Azure Function App is properly configured to support .NET 6.0 and is using the correct runtime version.
5. Language Workers Initialization:
-> Verify if there are any configuration issues preventing the initialization of language workers.

Additional Resources

Official Azure Functions Documentation