azure-functions-host: 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:

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

About this issue

Original URL
State: closed
Created 3 years ago
Reactions: 6
Comments: 16 (3 by maintainers)

Links to this issue

Why is an Azure Function on .NET 6 looking for System.ComponentModel Version 6.0.0.0? - Stack Overflow

Most upvoted comments

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>

lars-erik on Jan 18, 2021

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

aaronhudon on May 15, 2021

@SOFSPEEL I have confirmed that it works with the first workaround I wrote. It’s not wrong.

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

shibayan on Mar 9, 2021

@v-bbalaiagar The workaround is described in the first comment. The root cause of this problem is that the Azure Functions SDK deletes any assembly with a matching name without considering the assembly version. It is necessary to delete the assembly only if it is the same or lower version than the assembly that Functions Runtime has, and not delete it if it is a larger version.

shibayan on Mar 6, 2021