NU1201 for netcoreapp2.0 -> net461 project dependency using new csproj format/sdk, but not for classic csproj

[Tratcher]

NuGet product used (NuGet.exe | VS UI | Package Manager Console | dotnet.exe):
dotnet --version => 2.0.0-preview2-006479

VS version (if appropriate): 15.3 preview3 [26615.0.d15rel]

OS version (i.e. win10 v1607 (14393.321)): Win7 SP1

Worked before? Unknown

Detailed repro steps so we can see the same problem

Repro app: NetRef.zip

1. Create a new .NET Core Console App targeting netcoreapp2.0
2. Create a new .NET Core Class Library, edit the csproj, and change the TargetFramework to net461 (the same error occurs with net45-net47).
3. Add the class library as a dependency on the console app and build the project.

Result:
Error NU1201 Project ClassCoreSdk is not compatible with netcoreapp2.0 (.NETCoreApp,Version=v2.0). Project ClassCoreSdk supports: net461 (.NETFramework,Version=v4.6.1)

Other suggested things

• VS Intellesence works for this dependency, so the compiler appears to think it's valid.
• If I instead create a .NET Framework Class Library (e.g. classic .csproj format) targeting .NET 4.6.1 (or any other version) and add it as a dependency then it works fine.

Verbose Logs

logdump.txt

[analogrelay]

/cc @rrelyea @davidfowl @Eilon @muratg

[rrelyea]

Let's understand and fix in post V15.3P3/CLI2P2.
@anurse - let us know if you think this is a V15.3P3/CLI2P2 blocker.

[analogrelay]

I think we can avoid having it for CLI2P2. It only affects .NET Framework projects using the new SDK-based project system, which is rare, since existing projects will use the older project system.

[rrelyea]

This is because packages.config projects do not check compatibility during restore. Which is by design.
Build still fails for that scenario.

[valeriob]

Hi,
what's the story about this scenario, is it going to be supported ?
Thanks

[casfnq]

@anurse you might think it's rare, but we have a 700 project solution, and converting over existing libraries to .netstandard, so I have 45 errors of NU1201, so not so rare for me. As others move to the new format or create .netstandard projects then this will increase. @rrelyea if it is by design, what is the workaround?

[MisinformedDNA]

• Created a new .NET Core 2.0 class library
• Created a new Azure Function in .NET 4.6.1 (Functions don't yet support .NET Core)
• Make the Azure Function reference the class library (Note: No Nuget)

EXPECTED: Successfully added reference since they are both support .NET Standard 2.0
ACTUAL: Error NU1201 (same as OP)

Since they both support .NET Standard, there has to be a way to reference each other, right?

[Eirenarch]

I have hit this too trying to migrate existing project to .NET standard and the new project system. If I have old-school project file I can reference the net461 project from the .NET Standard class library if I use the new format I get the NU1201 error. Anyone found a workaround?

[mishra14]

Folks, thanks for your feedback! This issue appears to be identical to dotnet/standard#481

Please see that issue for workarounds and plan for the future.

[jasmeet321]

I have one class library project as my repository layer that in .netcore 2,0 framework and i am consuming this dll in Azure function project and its giving issue below

Severity Code Description Project File Line Suppression State
Error NU1201 Project Gamification.Services is not compatible with net461 (.NETFramework,Version=v4.6.1). Project Gamification.Services supports: netcoreapp2.0 (.NETCoreApp,Version=v2.0) TurnamentTimerFunctionApp E:\SportsFoundation\TurnamentTimerFunctionApp\TurnamentTimerFunctionApp.csproj 1

can anyone help