With the release of .NET Framework 4 this week, it is relevant to talk about migration issues you might run into when upgrading your applications to .NET 4. My team has put together a topic that describes the migration issues (formerly known as breaking changes) between the .NET Framework version 3.5 Service Pack 1 and the .NET Framework version 4. The change in terminology is to reflect the fact that not all changes introduced by a new version of the framework break your application; rather, these are changes in behavior discovered during design review and testing that could potentially impact an application.
We’ll update our portal (.NET Framework Version and Assembly Information) that points to different migration issues topics to include the .NET 4 version as well. So in a nutshell, these are the migration issues topics we have published so far and their locations: