Error CS8032 An instance of analyzer System.Text.Json.SourceGeneration.JsonSourceGenerator cannot be created from (...)

[augustoproiete]

Warning CS8032 System.Text.Json.SourceGeneration.JsonSourceGenerator cannot be created from ... when building a class library targeting net6.0 with .NET 6 RC1 SDK:0

Version Used:
SDK: 6.0.100-rc.1.21458.32
VS: 16.11.3

Steps to Reproduce:

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

  <PropertyGroup>
    <TargetFrameworks>net6.0;net5.0;netstandard2.0;net461</TargetFrameworks>

    <LangVersion>9.0</LangVersion>
    <Nullable>enable</Nullable>
    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
    <TreatSpecificWarningsAsErrors />
  </PropertyGroup>
 
</Project>

Expected Behavior:

No warnings or errors

Actual Behavior:

Error | CS8032 | An instance of analyzer System.Text.Json.SourceGeneration.JsonSourceGenerator cannot be created from C:\Program Files\dotnet\packs\Microsoft.NETCore.App.Ref\6.0.0-rc.1.21451.13\analyzers\dotnet\cs\System.Text.Json.SourceGeneration.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.. | NaturalStringExtensions (net6.0) | C:\augustoproiete\my-project\CSC | 1 | Active

Workaround:

Disable the warning CS8032:

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

  <PropertyGroup>
    <TargetFrameworks>net6.0;net5.0;netstandard2.0;net461</TargetFrameworks>

    <LangVersion>9.0</LangVersion>
    <Nullable>enable</Nullable>
    <NoWarn>$(NoWarn);CS8032</NoWarn>
    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
    <TreatSpecificWarningsAsErrors />
  </PropertyGroup>
 
</Project>

[svick]

I believe if you want to use .Net 6, you need VS 2022. The error message is trying to tell you that: .Net 6 requires Roslyn version 4.0 and VS 2019 does not support that.

[augustoproiete]

Thanks @svick. I suspect you're correct - though I have been using .NET 6.0.100-preview.4 and prior versions with VS2019 without issues, so it seems support for VS2019 has been dropped in more recent releases.

If you or anyone reading this know of any official announcement that .NET 6 requires VS2022 to work, please post here as I'm sure others will also expect .NET 6 to work with VS2019.

It would also be great if a check could be added, with a clear message that VS2019 is not supported.

[svick]

I have been using .NET 6.0.100-preview.4 and prior versions with VS2019 without issues, so it seems support for VS2019 has been dropped in more recent releases.

If you or anyone reading this know of any official announcement that .NET 6 requires VS2022 to work, please post here as I'm sure others will also expect .NET 6 to work with VS2019.

Both the download page for .Net 6 RC1 and its release notes say that only VS 2022 is supported.

It seems preview 4 was the last version to support VS 2019.

[martincostello]

There's also a recent change in dotnet/runtime to have the source generators multi-target for different Visual Studio versions: dotnet/runtime#59074

[jcouv]

Closing the issue as by-design. Thanks

[shunyh]

@augustoproiete

Yes, it does not support VS2019.