AutoCAD/Civil 3D should be able to load plugin with lower .net version

[soonhui]

Currently as it stands, AutoCAD/Civil 3D 2026 is on .net 8.0, and 2027 most likely will be on .net 10.0.

My point is that AutoCAD/Civil 3D should be able to load plugin with lower .net version. In other words, C3D 2026 which is written on .net 8.0 should be able to load .net plugin written in .net 6.0, and so on.

It is generally not possible now because I can foresee the AssemblyLoadContext issue, but even if that issue is solved, there is no guarantee that it can automatically load plugins written in lower .net version. 

This is important for us, because we generally don't want to do multi targeting framework ( whereby we target .net 8 and .net10 together), so we want to write our plugin/apps in the lowest .net version possible across all the supported C3D version.

[sreeparna_mandal]

Answered through internal ticket.

Yes, technically, .NET 10.0 can run .NET8.0 assemblies.
 
Till AutoCAD 2024, we had to build our custom dll on .NET Framework(last supported version was 4.8), but we migrated to .NET Core (which is a different runtime) from AutoCAD 2025 and as per official documentation, we began supporting .NET 8.0.
 
As per official documentation from Microsoft, (refer https://dotnet.microsoft.com/en-us/platform/support/policy) Long term support for .NET 8.0 is ending after this year and hence, we would always recommend our partners to update to .NET 10.0 for building plugins on AutoCAD 2027. 
Now, .NET 10.0 is backward compatible to .NET8.0, so custom dlls that can be NETLOADed into AutoCAD 2025 and 2026 should likely work on 2027 too. 

 
Based on Microsoft's LTS or STS of a .NET runtime, we keep updating the supported AutoCAD .NET runtime as well and hence, our strong recommendation for keeping the plugin versions updated as per AutoCAD's official documentation - About Managed .NET Compatibility - for stable development process.

Newer NET runtimes like .NET 10 generally backward compatible with .NET 8 assemblies, but in the case of AutoCAD plugins, what matters is the runtime that AutoCAD itself hosts!