I'm working on migrating a lot of old .Net Framework code right now, we're generally going with a complete rewrite but that's more to do with poor architectural decisions and the fact a lot of it is VB rather than C#.

It's pretty impressive that code largely written up to 20 years ago is now running on a modern OS, and it's using the latest Framework 4.8 with all the latest security updates and I can open VS2022 and hit run and it builds and runs fine. Our issues are the maintainability of the code and how it was written rather than the framework itself.

Meanwhile, a few years ago now, I had a web project written in typescript, it was only about a year out of date and npm install failed. Turns out one of dependencies needed to build something with python2, updating that needed a new version of webpack and that broke something else that never got an update to the newer webpack. Installing python2 didn't work either I think but I can't remember why.

There's systems I wrote for .Net over a decade ago that I can guarantee are still running in production and haven't been touched in all that time.

In short, I think I'm agreeing with you. It's painful but it's possible.