Ironically, 1.0 is the one that's the most problematic, because it never shipped in any version of Windows by default.
.NET 4.6 is the version that shipped in Win10 back in 2015. Win11 ships with .NET 4.8. Thus, both OSes can run any apps written for .NET 4.x out of the box. I would expect this to remain true for many years to come, given that Windows still supports VB6.
.NET 3.5 runtime (which supports apps written for .NET 2.0 and 3.0, as well) is also available in Win10 and Win11, but it's an optional feature that must be explicitly enabled - although the OS will automatically prompt you to do so if you try to run a .NET app that needs it.
Microsoft insisted on introducing a bunch of breaking changes into .NET Core (and all future .NET versions), making 4.8 a "dead end" in which many enterprise customers of mine have become stuck.
ASP.NET Web Forms sites are especially stuck, and on top of that I have customers that have developed Web Forms sites in VB.NET! Luckily there are some good bulk-conversion tools available now, but still, there is no smooth upgrade path for a lot of popular systems.
Similarly, Windows Communication Foundation, Workflow Foundation, and a bunch of other popular libraries or frameworks are dead in the water. SAP Crystal Reports is surprisingly common, but doesn't even have an official NuGet package!
That's a different story, though. The point is that old apps written against .NET Framework still work - you don't have to port them to .NET 5+ to get them to run on Win11.
Ironically, 1.0 is the one that's the most problematic, because it never shipped in any version of Windows by default.
.NET 4.6 is the version that shipped in Win10 back in 2015. Win11 ships with .NET 4.8. Thus, both OSes can run any apps written for .NET 4.x out of the box. I would expect this to remain true for many years to come, given that Windows still supports VB6.
.NET 3.5 runtime (which supports apps written for .NET 2.0 and 3.0, as well) is also available in Win10 and Win11, but it's an optional feature that must be explicitly enabled - although the OS will automatically prompt you to do so if you try to run a .NET app that needs it.
4.8x ships and still gets security updates
Microsoft insisted on introducing a bunch of breaking changes into .NET Core (and all future .NET versions), making 4.8 a "dead end" in which many enterprise customers of mine have become stuck.
ASP.NET Web Forms sites are especially stuck, and on top of that I have customers that have developed Web Forms sites in VB.NET! Luckily there are some good bulk-conversion tools available now, but still, there is no smooth upgrade path for a lot of popular systems.
Similarly, Windows Communication Foundation, Workflow Foundation, and a bunch of other popular libraries or frameworks are dead in the water. SAP Crystal Reports is surprisingly common, but doesn't even have an official NuGet package!
That's a different story, though. The point is that old apps written against .NET Framework still work - you don't have to port them to .NET 5+ to get them to run on Win11.
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