Azure Function cannot load ApplicationInsights assembly

Question

I have an azure function app that is failing to run. I seem to have fallen into Versioning Hell with application insights.

On the Function App page it displays the error:

Microsoft.Azure.WebJobs.Extensions.ApplicationInsights: Could not load file or assembly 'Microsoft.Azure.WebJobs.Logging.ApplicationInsights, Version=3.0.27.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. The system cannot find the file specified.

This function app contains one function. I include the following packages:

    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.ApplicationInsights" Version="1.0.0-preview4" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Logging.ApplicationInsights" Version="3.0.27.0" />

I have tried removing the keys APPINSIGHTS_INSTRUMENTATIONKEY and APPLICATIONINSIGHTS_CONNECTION_STRING. Now I get a different error:

Microsoft.Azure.WebJobs.Script: The Application Insights Extension is installed but is not properly configured. Please define the "APPLICATIONINSIGHTS_CONNECTION_STRING" app setting.

What do I have to do to get my Azure Function app to start running?

I than attempted to create a whole new function app and got the following error:

Microsoft.Azure.WebJobs.Extensions.ApplicationInsights: Method not found: 'Void Microsoft.Azure.WebJobs.Logging.ApplicationInsights.ApplicationInsightsLoggerOptions.set_SamplingSettings(Microsoft.ApplicationInsights.WindowsServer.Channel.Implementation.SamplingPercentageEstimatorSettings)'.

Answer 1

I have an unsatisfactory answer, but I'll add what I learnt for the next person who is fumbling around with this:

• Check the runtime version of your function app. When I finally got it working, it was working on runtime version 3.2.0.0. By the time you read this, runtime version 4.* might have stabilized so these version problems have been solved, but in October 2021 it's all just too hard. See this link

• If you are on runtime version 3.2.0.0, do NOT put a reference to Application Insights packages in your .csproj file (Microsoft.Azure.WebJobs.Extensions.ApplicationInsights nor Microsoft.Azure.WebJobs.Logging.ApplicationInsights)

Once I set the runtime version to ~3 and removed the application insights package, I had a working Azure function.