Could not load file or assembly System.Collections.Immutable

[Alxandr]

After upgrading one of my dependencies I'm getting the following build error:

C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error : System.IO.FileLoadException: Could not load file or assembly 'System.Collections.Immutable, Version=1.2.4.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Could not find or load a specific file. (Exception from HRESULT: 0x80131621) [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error : File name: 'System.Collections.Immutable, Version=1.2.4.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' ---> System.IO.FileLoadException: Could not load file or assembly 'System.Collections.Immutable, Version=1.2.4.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at System.Runtime.Loader.AssemblyLoadContext.LoadFromPath(IntPtr ptrNativeAssemblyLoadContext, String ilPath, String niPath, ObjectHandleOnStack retAssembly) [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath) [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at System.Reflection.Assembly.LoadFrom(String assemblyFile) [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at System.Reflection.Assembly.LoadFromResolveHandler(Object sender, ResolveEventArgs args) [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at System.AppDomain.InvokeResolveEvent(ResolveEventHandler eventHandler, RuntimeAssembly assembly, String name) [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at System.Reflection.RuntimeAssembly.GetExportedTypes(RuntimeAssembly assembly, ObjectHandleOnStack retTypes) [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at System.Reflection.RuntimeAssembly.GetExportedTypes() [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at MakeFunctionJson.FunctionJsonConverter.TryGenerateFunctionJsons() [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :    at MakeFunctionJson.FunctionJsonConverter.TryRun() [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :  [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk.Functions.Build.targets(41,5): error :  [C:\Git\PolicyStaging\src\PolicyStaging\PolicyStaging.csproj]
C:\Users\D45\.nuget\packages\microsoft.net.sdk.functions\1.0.29\build\netstandard1.0\Microsoft.NET.Sdk

I've tried to create a simple reproduction in a new project but I'm unfortunately unable to, so it's a bit hard to say what exactly is causing this. Mostly, I'm posting this issue here in hopes that someone will have suggestions on how to resolve it.

[Alxandr]

I managed to make a pretty simple reproduction: https://gist.github.com/Alxandr/de2988691b5a8546a36b085ba009c78f

The gist of it;

1. Make a new azure functions project.
2. Add a dependency to System.Collections.Immutable 1.6.0.
3. Use dependency in a function (might need to be in the function signature).
4. Build.

[AArnott]

It looks like it works up to S.C.I. 1.5.0. 1.6.0 is the first one to cause a failure.

[simonvane]

I had a similar issue at runtime when some library code my function was using called ToImmutableList.

The issue occurs with both System.Collections.Immutable 1.6.0 and 1.7.0. Downgrading to version 1.5.0 resolved the issue after a very considerable amount of wasted time.

System.MissingMethodException
Method not found: 'System.Collections.Immutable.ImmutableList`1<!!0> System.Collections.Immutable.ImmutableList.ToImmutableList(Builder<!!0>)'.

[liliankasem]

Looks like PR to fix this issue has been merged