Migrate .NET Framework 4.8 / .NET Core 5 to .NET 9 (.NET 10)
Hello folks 👋!
I maintain a solution that contains over 400 projects. They are a mix between .NET Framework 4.8 / .NET Core 5 / .NET Standard 2.0. The majority of web projects are built on .NET Framework with Microsoft.Owin, and some of them still use the old non-SDK project format. There are also several WinForms back-office applications, which we are planning to migrate to web.
I’m aware that not everything can be upgraded, i.e. legacy libraries that are already out of support. My current approach is to write wrappers around such dependencies, and then gradually replace those wrappers with modern equivalents.
Do you have any recommendations on upgrading such a large system? Any useful articles or guidelines you could share?
I can provide additional details if necessary. However, due to NDA, I can not share certain internal information.
5 Replies
Sure, I know that. But they are using some msbuild tricks, so it should be not a very straightforward task
I wish, haha
that's good point
try-convert exists i guess
but it's not super great?
upgrading framework style to sdk style isn't a trivial process either way. there are many traces a conversion might leave in the project file which aren't actually necessary
or which have more modern alternatives
it's not really something you do in a day or 2 for 400 projectsYes, another team member estimated that as 3 sprints for migration itself and another 1-2 to regression and resolving issues
So it is like 4-5 months
VS 2026 comes with a migration tool along with Copilot and Claude Sonnet 4
ok that seems a bit excessive lol