Unable to start V3 Azure Function : Could not load file or assembly

[StefH]

Function csproj:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <AzureFunctionsVersion>v3</AzureFunctionsVersion>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.13.1" />
    <PackageReference Include="Microsoft.Azure.Functions.Extensions" Version="1.0.0" />
    <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="3.1.2" />
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="3.0.5" />
  </ItemGroup>

  <ItemGroup>
    <None Update="host.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <CopyToPublishDirectory>Always</CopyToPublishDirectory>
    </None>
    <None Update="local.settings.development.json">
      <DependentUpon>local.settings.json</DependentUpon>
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <CopyToPublishDirectory>Never</CopyToPublishDirectory>
    </None>
  </ItemGroup>
</Project>

Azure Function portal settings:

Unable to start Azure Function, error message in Azure Portal is:

Error:

The function runtime is unable to start. My.FunctionApp: Could not load file or assembly 'Microsoft.Extensions.Configuration, Version=3.1.2.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified. . System.Private.CoreLib: Could not load the specified file.

Notes

Note that this is Azure Function is running on a Linux App Service plan.

[StefH]

Example project:
https://github.com/StefH/AzureFunctionsV3

[tewleap]

I am having the same issue, haven't found a solution yet.

[AlexanderRettkowski]

I stumbled upon a similar issue and was able to solve it by setting the Microsoft.NET.Sdk.Functions dependency to 3.0.3. You might try that as well.
The issue might be linked to something like this one: Azure/azure-functions-host#5747

[StefH]

When using version 3.0.3 I get this error:

>>>

Note that I only get an error when running on a Linux App Service, when deploying the same code (3.0.3 or 3.0.5) on Windows App Service, it works fine.

[AlexanderRettkowski]

Have you tried adding the necessary dependencies as PackageReferences manually? AddEnvironmentVariables() relies on

• Microsoft.Extensions.Configuration.EnvironmentVariables
• Microsoft.Extensions.Configuration
• Microsoft.Extensions.Configuration.Abstractions
• Microsoft.Extensions.Primitives

I don't know that much about the runtime environments but I just did a few short experiments and fell upon the same issue as you when not adding those references. Depending on how you're loading the json files you might want to add

• Microsoft.Extensions.Configuration.FileExtensions
• Microsoft.Extensions.Configuration.Json

as well. I tested version 3.1.2 for all of them.

[brettsam]

Trying to narrow down the issue -- what if you try using an earlier version of Microsoft.Extensions.Logging.Console -- does 3.1.1 work?

@AlexanderRettkowski -- does yours also only reproduce in Linux?

@StefH -- In your screenshot, it says you're using functions version ~3 yet running a v2 host, which seems broken. Is this a Linux Consumption app?

[StefH]

@brettsam I'm nor running on V2 host (at least I think I am not..) Where did you see that I'm running at V2?

I did not yet try 'Microsoft.Extensions.Logging.Console - 3.1.1'

[brettsam]

From your screenshot above -- it appears that you've got ~3 set, yet a v2 runtime is being used.

Is this a Linux Consumption or App Service Plan? + @balag0 / @divyagandhii in case they've seen this in Linux apps.

[StefH]

I see your point.

A function running on a Windows App Plan, I see this:

A function running on a Linux App Plan, I see indeed this:

And the docker image which is used has this info:
microsoft/azure-functions-dotnet-core2.0:2.0
And logging:

2020-03-15 18:19:43.863 INFO  - Pulling image from Docker hub: microsoft/azure-functions-dotnet-core2.0:2.0
2020-03-15 18:19:45.029 INFO  - 2.0 Pulling from microsoft/azure-functions-dotnet-core2.0
2020-03-15 18:19:45.031 INFO  -  Digest: sha256:543d0a584daf8c4f9ff003c817da5a9e42c079e5526145470c350096fe29c1e9
2020-03-15 18:19:45.033 INFO  -  Status: Image is up to date for microsoft/azure-functions-dotnet-core2.0:2.0
2020-03-15 18:19:45.036 INFO  - Pull Image successful, Time taken: 0 Minutes and 1 Seconds
2020-03-15 18:19:45.048 INFO  - Starting container for site
2020-03-15 18:19:45.050 INFO  - docker run -d -p 9561:80 --name stef-function-app-linux-v3_0_21076afa -e WEBSITE_CORS_ALLOWED_ORIGINS=https://functions.azure.com,https://functions-staging.azure.com,https://functions-next.azure.com -e WEBSITE_CORS_SUPPORT_CREDENTIALS=False -e WEBSITES_ENABLE_APP_SERVICE_STORAGE=true -e WEBSITE_SITE_NAME=stef-function-app-linux-v3 -e WEBSITE_AUTH_ENABLED=False -e PORT=80 -e WEBSITE_ROLE_INSTANCE_ID=0 -e WEBSITE_HOSTNAME=stef-function-app-linux-v3.azurewebsites.net -e WEBSITE_INSTANCE_ID=31c0e435accff6d7fdc48c7918f57b1c0cbe27c6465fe990a7f0e8eeeac689f1 -e HTTP_LOGGING_ENABLED=1 microsoft/azure-functions-dotnet-core2.0:2.0  

2020-03-15 18:19:45.644 INFO  - Starting container for site
2020-03-15 18:19:45.646 INFO  - docker run -d -p 5815:8081 --name stef-function-app-linux-v3_0_21076afa_middleware -e WEBSITE_CORS_ALLOWED_ORIGINS=https://functions.azure.com,https://functions-staging.azure.com,https://functions-next.azure.com -e WEBSITE_CORS_SUPPORT_CREDENTIALS=False -e WEBSITES_ENABLE_APP_SERVICE_STORAGE=true -e WEBSITE_SITE_NAME=stef-function-app-linux-v3 -e WEBSITE_AUTH_ENABLED=False -e WEBSITE_ROLE_INSTANCE_ID=0 -e WEBSITE_HOSTNAME=stef-function-app-linux-v3.azurewebsites.net -e WEBSITE_INSTANCE_ID=31c0e435accff6d7fdc48c7918f57b1c0cbe27c6465fe990a7f0e8eeeac689f1 -e HTTP_LOGGING_ENABLED=1 appsvc/middleware:2001061754 /Host.ListenUrl=http://0.0.0.0:8081 /Host.DestinationHostUrl=http://172.16.10.2:80 /Host.UseFileLogging=true 

2020-03-15 18:19:46.336 INFO  - Initiating warmup request to container stef-function-app-linux-v3_0_21076afa for site stef-function-app-linux-v3
2020-03-15 18:19:50.892 INFO  - Container stef-function-app-linux-v3_0_21076afa for site stef-function-app-linux-v3 initialized successfully and is ready to serve requests.
2020-03-15 18:19:50.893 INFO  - Initiating warmup request to container stef-function-app-linux-v3_0_21076afa_middleware for site stef-function-app-linux-v3
2020-03-15 18:19:51.126 INFO  - Container stef-function-app-linux-v3_0_21076afa_middleware for site stef-function-app-linux-v3 initialized successfully and is ready to serve requests.

[balag0]

@ankitkumarr This app has linux fx version set to DOCKER|microsoft/azure-functions-dotnet-core2.0:2.0
Does Functions extension version override this or do we have update linux fx version to point to 3.0 images

[divyagandhisethi]

This is a known issue - Azure/azure-functions-host#5559 . The issue mentions only CLI client and we fixed it there but I think this issue needs to be fixed for portal and other clients as well.

[StefH]

@brettsam & @balag0 :
I have a feeling that something has changed since the moment I created that Linux App Services based Azure Function (this is called ...v3).

When using the new UI in Azure Portal, I see this for the old Function with these settings (an error is visible...):

However, I just created a new function (this is called ...v3a), and this looks like:

Note that initially the stack settings where empty, but I manually changed these to this:

However after deploying (via Azure Pipelines, https://github.com/StefH/AzureFunctionsV3/blob/master/azure-pipelines.yml) the Function is broken again:

UPDATE
By default the version 2.0 from the docker is used?
When I look at the project page https://github.com/Azure/azure-functions-docker/ I see that also a 3.0 version is available.

But when using this 3.0 docker, the Function is still broken after deployment.

UPDATE 2020-03-30
When using the correct runtimeStack ==> The 3.0 docker version, the Function works correct.

See excerpt from YAML file below:

    - task: AzureFunctionApp@1
      displayName: 'Deploy Function via AzureFunctionApp@1'
      inputs:
        azureSubscription: '***'
        appType: functionAppLinux
        appName: $(webAppName)
        package: '$(Pipeline.Workspace)/**/FunctionsAppV3.zip'
        runtimeStack: 'DOCKER|mcr.microsoft.com/azure-functions/dotnet:3.0'

For a working example see (https://github.com/StefH/AzureFunctionsV3/blob/master/azure-pipelines.yml#L80)

[StephenCleary]

I believe I'm having the same issue. It looks like the RemoveRuntimeDependencies task (from assembly "$.nuget\packages\microsoft.azure.webjobs.script.extensionsmetadatagenerator\1.1.5\tools\net46\Microsoft.Azure.WebJobs.Script.ExtensionsMetadataGenerator.dll") is waaaay too liberal about what files it likes to remove from the output directory.

• Microsoft.NET.Sdk.Functions 3.0.3 - works fine. RemoveRuntimeDependencies is not run at all.
• Microsoft.NET.Sdk.Functions 3.0.4 - RemoveRuntimeDependencies can cause GenerateFunctionsExtensionsMetadata to fail due to "could not load file or assembly".
• Microsoft.NET.Sdk.Functions 3.0.5 - RemoveRuntimeDependencies has been moved after GenerateFunctionsExtensionsMetadata so the build passes and the functions are found, but that doesn't help much because we still get "could not load file or assembly" at runtime.