Hey Matheus,

While I haven’t gone through this exact migration, here’s what I recommend based on how OutSystems 11 handles .NET versions: Since the platform documentation states that the server supports .NET Framework 4.8 (and later .4.8.1 for newer builds), the safest route when moving your extension (built originally for .NET 4.6.1) to a new server environment (e.g., Windows Server 2022) is to open your extension in Integration Studio, retarget it to .NET 4.8, recompile, republish and test. This ensures compatibility with the platform’s supported runtime and avoids potential runtime mismatches. If your extension works fine at 4.6.1 today, you might not have to retarget — but upgrading is low-risk and future-proof.

I have attached some reference link for the same context:

• System requirements for OutSystems 11 show “Microsoft .NET Framework … 4.8 (supported since Platform Server 11.35). Click Here

• Platform release notes mention “Added support for .NET Framework 4.8.1. Click Here
  
  

Hope this input will help you / give some hint points.

Thanks and Regards,
Akshay Deshpande

Luckily, an upgrade from 4.6.1 to 4.8.1 is usually easy. I would place OutSystems Extensions as the easiest, since these are small projects with not a lot of ASP.NET or other frameworks attached. Because the two versions share the same CLR version, you can use 4.6.1 projects in 4.8.1 projects, and the older project will run as a 4.8.1 version (There are some exceptions, but if it runs, it uses the newer runtime). 

When you open an extension in Visual Studio, you can right-click on the project and go to Properties. Here, you can change the TargetFramework to 4.8.1. Then check your NuGet packages for any upgrades if used. 

When 4.8.1 is not in the list, please install the dotbet 4.8.1 Dev Pack, which enables you to develop 4.8.1 apps

https://dotnet.microsoft.com/en-us/download/dotnet-framework/net481