Roll-forward from 3.1 -> 6.0 fails

I was playing with some 3.1 samples and trying to roll them forward to 6.0. That didn’t work. I’m unaware of a compatibility issue that would have caused this. If I run the 3.1 sample on the 3.1 runtime, it works. If I update the sample to target 6.0, then it similarly works. I tried this with multiple samples.

I know we made some changes during .NET 5 or 6 where we changed the way the GPIO library was packaged, particularly as it relates to Windows (although I’m on Linux).

I have three basic questions:

• Is this compatibility issue known?
• If so, is it documented?
• Why does it show up as a failure to create CoreCLR?

Here is what I see:

rich@raspberrypi:~/iot/src/devices/ShiftRegister/samples $ dotnet bin/Debug/netcoreapp3.1/ShiftRegister-driver.dll
It was not possible to find any compatible framework version
The framework 'Microsoft.NETCore.App', version '3.1.0' (arm64) was not found.
  - The following frameworks were found:
      6.0.0 at [/home/rich/iot/.dotnet/shared/Microsoft.NETCore.App]
      6.0.2 at [/home/rich/iot/.dotnet/shared/Microsoft.NETCore.App]

You can resolve the problem by installing the specified framework and/or SDK.

The specified framework can be found at:
  - https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=3.1.0&arch=arm64&rid=debian.11-arm64
rich@raspberrypi:~/iot/src/devices/ShiftRegister/samples $ dotnet --roll-forward Major bin/Debug/netcoreapp3.1/ShiftRegi
ster-driver.dll
Failed to create CoreCLR, HRESULT: 0x80070057
rich@raspberrypi:~/iot/src/devices/ShiftRegister/samples $ ~/.dotnet/dotnet bin/Debug/netcoreapp3.1/ShiftRegister-driver
.dll
Driver for ShiftRegister
Register bit length: 8
Using GPIO
Light up three of first four LEDs
Light up all LEDs, with ShiftBit
Dim up all LEDs, with ShiftBit
^CWrite a set of values with ShiftByte
Value: 1

Note: The dotnet in the path has just .NET 6. The .NET at /.dotnet has .NET Core 3.1 and .NET 6.

/cc @vitek-karas

[vitek-karas]

Yes, we removed winmd (WinRT) support in .NET 5 - intentionally.

[krwq]

[Triage] Thanks @vitek-karas in that case the compatibility problem is expected and new version of .NET IoT must be used. Closing the issue as by design.