Microsoft.NET.Sdk.Functions >3.0.3 can't find dependency DLLs

[josh-endries]

If I have a v3 Function using netcoreapp3.1 that references a netstandard2.1 project, and that project includes a dependency. The Function can't load at least one of those dependency assemblies. For example, the Function project:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <AzureFunctionsVersion>v3</AzureFunctionsVersion>
    <Version>1.0</Version>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="3.0.9" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\MyDependency.csproj" />
  </ItemGroup>
</Project>

The dependency project:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netstandard2.1</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="System.Interactive.Async" Version="4.1.1" />
  </ItemGroup>
</Project>

The error:

[8/31/2020 7:56:46 PM] System.Private.CoreLib: Exception while executing function: Foo. MyProject: Could not load file or assembly 'System.Interactive.Async, Version=4.1.0.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263'. The system cannot find the file specified.

Adding the problem package directly into my Function app didn't help, but changing the SDK package back to 3.0.3 works. It seems to stop working with 3.0.4.

One thing to note is that the error references 4.1.0.0 but the package and DLL itself (in file explorer property details) both seem to be 4.1.1, so it might be something with this package specifically... I did try to use 4.0.0 of that package in both projects and still had the same issue (it couldn't find the v4.0.0.0 DLL). I think in all cases, or all the ones I checked at least, the DLL was actually in the bin folder.

I suspect this is the same issue as Azure/azure-functions-dotnet-extensions#41

[giuliov]

I noticed a similar issue after updating from 3.0.2 to 3.0.9: about 80 dependent DLLs disappeared from the publish output, I had to rollback.

[giuliov]

This is a serious issue for Aggregator, can someone take a look at this issue and give some feedback?

[briangardner]

We're seeing this same issue with the Microsoft.Extensions.Caching.* libraries.

[haintechdev]

I have the same issue with version 3.0.11 of the Microsoft.NET.Sdk.Functions package i try and the error began in version 3.0.9, older version work fine.

[zhaparoff]

Please refer to Azure/azure-functions-host#5894 for the root cause and the available workarounds.
But, primarily, adding

<PropertyGroup>
    <_FunctionsSkipCleanOutput>true</_FunctionsSkipCleanOutput>
</PropertyGroup>

to the project file is the best solution for now and should help.