Wpf: MC1000: Unknown build error Could not find assembly System.Web

[goldenc]

• .NET Core Version: tried both with SDK version 3.1.102 and 3.0.103
• Windows version: 1809 Build 07763.973
• Does the bug reproduce also in WPF for .NET Framework 4.8?: No

• Is this bug related specifically to tooling in Visual Studio (e.g. XAML Designer, Code editing, etc...)? No

  Cannot build Wpf project using dotnet cli:
  I have added a global.json config file as follows:

{
    "sdk": {
        "version": "3.0.103",
        "rollForward": "disable"
    }
}

With this the solution does build when using Visual Studio but when I build using the command line (dotnet build mySolution.sln) it fails with the below error.

If I change to use the latest SDK (3.1.102) it fails with the same error in both VS and on the command line. VS version is 16.4.5

Actual behavior:
C:\Program Files\dotnet\sdk\3.0.103\Sdks\Microsoft.NET.Sdk.WindowsDesktop\targets\Microsoft.WinFX.targets(243,9): error MC1000: Unknown build error, 'Could not find assembly 'System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Either explicitly load this assembly using a method such as LoadFromAssemblyPath() or use a MetadataAssemblyResolver that returns a valid assembly.' [C:\dev\src\mySol\WpfAdditions\Shared.WpfAdditions.csproj]

Seems quite similar to #2274 just for a different assembly, not sure if it is basically the same issue.

Expected behavior:
Project builds correctly.

[vatsan-madhavan]

Can you share a repro project that can be used to investigate this ? Something small/self-contained that picks out the essential characteristics of the project that is affected by this bug would be nice. Chances are good that the NuGet references are the key.

/cc @rladuca, @nguerrera

[vatsan-madhavan]

Do you still have this problem when building against the latest .NET Core 3.1 SDK (3.1.103 or 3.1.201)?

[msftbot[bot]]

This issue has been automatically marked as stale because it has marked as requiring author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment. Thank you for your contributions!

[jnm2]

I'm getting this on a small .NET Framework 4.8 WPF class library when I hand-convert it from legacy csproj to SDK-style csproj. SDK version is 3.1.300.

C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk.WindowsDesktop\targets\Microsoft.WinFX.targets(225,9): error MC1000: Unknown build error, 'Could not find assembly 'System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Either explicitly load this assembly using a method such as LoadFromAssemblyPath() or use a MetadataAssemblyResolver that returns a valid assembly.'

It goes away when I remove the package reference to the DevExpress library:

<Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">

  <PropertyGroup>
    <TargetFramework>net48</TargetFramework>
    <UseWPF>true</UseWPF>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="DevExpress.Wpf.Grid" Version="20.1.3" />
  </ItemGroup>

</Project>

Obviously this may not be your problem, but any tips to take back to DevExpress would be great.

[jnm2]

The workaround seems to be to put this in the csproj:

  <ItemGroup>
    <!-- Workaround for https://github.com/dotnet/wpf/issues/2648#issuecomment-635674683 -->
    <Reference Include="System.Web" />
  </ItemGroup>