Azure Function - Failed to start a new language worker for runtime: dotnet-isolated

Question

I have a dotnet 5 function app that I've been building and deploying from a devops pipeline for a couple of weeks.

Following the most recent release, I see the following error in App Insights:

Exception type System.TimeoutException

Exception message The operation has timed out.
LogLevel Error
prop__{OriginalFormat} Failed to start a new language worker for runtime: dotnet-isolated.
Category Microsoft.Azure.WebJobs.Script.Workers.Rpc.RpcFunctionInvocationDispatcher
System.TimeoutException: The operation has timed out.
at Microsoft.Azure.WebJobs.Script.Grpc.GrpcWorkerChannel.StartWorkerProcessAsync()

csproj file:

<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net5.0</TargetFramework>
<Nullable>enable</Nullable>
</PropertyGroup>

<ItemGroup>
<None Remove="local.settings.json" />
</ItemGroup>

<ItemGroup>
<Content Include="local.settings.json">
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
<CopyToPublishDirectory>Never</CopyToPublishDirectory>
</Content>
</ItemGroup>

<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.Mvc.Abstractions" Version="2.2.0" />
<PackageReference Include="Microsoft.AspNetCore.Mvc.Core" Version="2.2.5" />
<PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.4.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Abstractions" Version="1.0.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http" Version="3.0.13" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Storage" Version="4.0.4" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.0.4" />
<PackageReference Include="Microsoft.Azure.Services.AppAuthentication" Version="1.6.1" />
<PackageReference Include="Microsoft.Data.SqlClient" Version="3.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="5.0.8">
<PrivateAssets>all</PrivateAssets>
<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>
<PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="5.0.0" />
<PackageReference Include="NSwag.AspNetCore" Version="13.13.2" />
<PackageReference Include="Serilog.AspNetCore" Version="4.1.0" />
<PackageReference Include="Serilog.Sinks.ApplicationInsights" Version="3.1.0" />
<PackageReference Include="Serilog.Sinks.MSSqlServer" Version="5.6.0" />
</ItemGroup>

<ItemGroup>
<ProjectReference Include="..\Infrastructure\SmsRouter.EntityFramework\SmsRouter.EntityFramework.csproj" />
<ProjectReference Include="..\infrastructure\SmsRouter.GovNotify\SmsRouter.GovNotify.csproj" />
<ProjectReference Include="..\Infrastructure\SmsRouter.Utrn\SmsRouter.Utrn.csproj" />
<ProjectReference Include="..\SmsRouter.Core\SmsRouter.Core.csproj" />
</ItemGroup>

<ItemGroup>
<None Update="host.json">
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</None>
</ItemGroup>

</Project>

host.json:

{
  "version": "2.0"
}

Function App Configuration:

[
  {
    "name": "AzureWebJobsStorage",
    "value": "DefaultEndpointsProtocol=https;AccountName=storesmsroutermsdn;AccountKey=<my key is here>;EndpointSuffix=core.windows.net",
    "slotSetting": false
  },
  {
    "name": "FUNCTIONS_EXTENSION_VERSION",
    "value": "~3",
    "slotSetting": false
  },
  {
    "name": "FUNCTIONS_WORKER_RUNTIME",
    "value": "dotnet-isolated",
    "slotSetting": false
  },
  {
    "name": "WEBSITE_CONTENTAZUREFILECONNECTIONSTRING",
    "value": "DefaultEndpointsProtocol=https;AccountName=storesmsroutermsdn;AccountKey=<my key is here>;EndpointSuffix=core.windows.net",
    "slotSetting": false
  },
  {
    "name": "WEBSITE_CONTENTSHARE",
    "value": "func-smsrouter-msdn-01b300",
    "slotSetting": false
  },
  {
    "name": "WEBSITE_ENABLE_SYNC_UPDATE_SITE",
    "value": "true",
    "slotSetting": false
  },
  {
    "name": "WEBSITE_RUN_FROM_PACKAGE",
    "value": "1",
    "slotSetting": false
  }
]

Function Definition

[Function("HttpExample")]
    public static HttpResponseData Run([HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequestData req,
        FunctionContext executionContext)
    {
        var response = req.CreateResponse(HttpStatusCode.OK);
        response.Headers.Add("Content-Type", "text/plain; charset=utf-8");

        response.WriteString("Welcome to Azure Functions!");

        return response;
    }

Has anyone else run into this problem?

Note: I have created a support ticket for this via the Azure Portal - the id is 2106280050000196. Github issue here

I've also tried deploying to a fixed app service plan (rather than consumption) but continued to hit the same problem.

Answer 1

Hi @Rob Bowman , I understand that you are working with Microsoft Support on the issue. If you have any questions, please reach out to us so that we can help you.