[Question] Referencing .NET Framework WinForms from .NET Core WinForms

[janseris]

.NET version

8.0.1

Did it work in .NET Framework?

Not tested/verified

Did it work in any of the earlier releases of .NET Core or .NET 5+?

No response

Issue description

How is WinForms NET Core -> NET Framework intended to work?
I noticed that when I create old csproj style WinForms, Visual Studio does not report any warnings
When I switch to new csproj and change target framework moniker to .NET Framework 4.8, I start receiving warning which afaik cannot be disabled.
Using new csproj structure allows me to use Sync Namespaces feature in Visual Studio which is very important in large projects.

Severity	Code	Description	Project	File	Line	Suppression State
Warning	NU1702	ProjectReference 'C:\Users\Jan\Desktop\prace\WinFormsCsProjNewOldTest\WinFormsNetFrameworkClassLibraryNewProjectStructure\WinFormsNetFrameworkClassLibraryNewProjectStructure.csproj' was resolved using '.NETFramework,Version=v4.8' instead of the project target framework '.NETCoreApp,Version=v8.0'. This project may not be fully compatible with your project.	WinFormsNetCore	C:\Program Files\Microsoft Visual Studio\2022\Community\MSBuild\Current\Bin\amd64\Microsoft.Common.CurrentVersion.targets	1860	

Why is that? Is it supposed to be there?

Steps to reproduce

https://github.com/janseris/WinFormsCsProjNewOldTest

[elachlan]

Hi @janseris,

There are a couple of options listed below

1. Multi-target. Specify multiple targets under the TargetFrameworks property. See: https://learn.microsoft.com/en-us/nuget/create-packages/multiple-target-frameworks-project-file

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

  <PropertyGroup>
    <TargetFrameworks>net6.0;net48</TargetFrameworks>
    <Description>Sample project that targets multiple TFMs</Description>
  </PropertyGroup>

</Project>

2. Use the netstandard2.0 TargetFramework for your class library
3. Migrate everything to .NET core
4. Stick with .net4.8

Hope that helps.

[janseris]

Hi @janseris,

There are a couple of options listed below

1. Multi-target. Specify multiple targets under the `TargetFrameworks` property. See: https://learn.microsoft.com/en-us/nuget/create-packages/multiple-target-frameworks-project-file

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

  <PropertyGroup>
    <TargetFrameworks>net6.0;net48</TargetFrameworks>
    <Description>Sample project that targets multiple TFMs</Description>
  </PropertyGroup>

</Project>

2. Use the `netstandard2.0` `TargetFramework` for your class library

3. Migrate everything to .NET core

4. Stick with .net4.8

Hope that helps.

But why is the warning dependent on just having different style of csproj?
I am working without any issues referencing .NET Framework WinForms Control library from a .NET Core project in production without multitargeting.

[elachlan]

I have no idea. But if you want to have both .net framework and .net core projects, you either multi-target or use .netstandard 2.0.

You might have better luck getting a more in-depth answer on https://stackoverflow.com/

[merriemcgaw]

I am going to convert this issue to a discussion for further conversation, but I agree with @elachlan that your best bet might be another forum.