Could not load file or assembly 'System.Text.Encoding.CodePages, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.

Repro steps

Provide the steps required to reproduce the problem:

1. Create function app project
2. Install System.Text.Encoding.CodePages nuget package
3. Adding Encoding.RegisterProvider(CodePagesEncodingProvider.Instance); to function
4. Run function app

Expected behavior

Function app is executed without error

Actual behavior

The following error occurs and the function cannot be executed.

[2021-01-15T07:00:17.378Z] A host error has occurred during startup operation 'e356b46a-f0fb-44a1-8494-df0ad91f3d36'.
[2021-01-15T07:00:17.380Z] FunctionApp34: Could not load file or assembly 'System.Text.Encoding.CodePages, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. 指定されたファイルが見つかりません。.
Value cannot be null. (Parameter 'provider')

Known workarounds

• Adding _FunctionsSkipCleanOutput setting
• Downgrade System.Text.Encoding.CodePages to v4.7.1

[lars-erik]

I have the same problem. The publish targets remove a lot of stuff.
The System.Text.Encoding.CodePages.dll is copied into bin/runtime/netstandard2.0.
It seems like files under bin/runtime/** are not probed at all.
I’ve tried this with both V2 and V3 runtime, including pretty much all framework targets since netstandard2.0.

I managed to get the file copied to the bin folder locally with an extra target in my .csproj, but I couldn’t figure which target / filegroup / property to use in order to include the file in the .zip that is published.
So for now I grudgingly copy the file into the function’s bin folder using the kudu console.

Let me know if I can help by providing more details. Here’s my targets:

  <Target Name="ForceCopyCodePages" AfterTargets="_FunctionsBuildCleanOutput">
    <Message Importance="High" Text="Copying messed up deps to $(OutputPath)" />
    <Copy SourceFiles="$(OutputPath)bin\runtimes\win\lib\netcoreapp2.0\System.Text.Encoding.CodePages.dll"
          DestinationFolder="$(OutputPath)bin"/>
  </Target>
  <Target Name="ForcePublishCodePages" AfterTargets="_FunctionsPostPublish">
    <Message Importance="High" Text="Copying messed up deps for publish to $(PublishDir)bin" />
    <Copy SourceFiles="$(OutputPath)bin\runtimes\win\lib\netcoreapp2.0\System.Text.Encoding.CodePages.dll"
          DestinationFolder="$(PublishDir)bin"/>
  </Target>

[aaronhudon]

Why is this about to be closed? I am seeing the issue myself running latest Functions SDK 3.0.12