Using the NET Upgrade Assistant, it informed me that it couldn't perform the migration since the code was not in .NET Full Framework. For code to operate in the new NET world, is that a requirement or is that a assistant issue? Can I just create a new project and manually move everything to it?

The error is

[09:22:29 ERR] Support for Web Forms is limited to .NET Full Framework. To learn more please read: aka.ms/migrate-web-forms [09:22:29 ERR] Project C:\Projects\IC\VS2022\SentryServices_NET5_Dev\WWW\www.csproj uses feature(s) that are not supported.

CodePudding user response：

Well, web forms is so old, it's no longer supported in .NET Core or .NET 5.

You can read the link the error message gave you, to find out what you can do about that.

You will have to rewrite considerable parts of your app. While it is possible to just copy over source code files, that only works if the code written would work under .NET 5. If it wouldn't, like web forms, then there is no real migration path other than rewrite it.