Did anybody encounter portability issues when performing .NET runtime upgrade (e.g switching from 2.0 -> 3 -> 3.5 -> 4 -> 4.5)?
I couldn’t find any proof for the fact that upgrading to a higher version of the runtime wouldn’t affect the behavior of my application (I guess this should be so, but, well, there are always hidden caveats).
There are always a few changes that could change the behavior of existing code, but these are in most cases rare edge cases and are kept to a minimum. You can find a list of breaking changes for recent releases of Visual Studio:
Visual C# 2012 RC Breaking Changes
Visual C# 2010 Breaking Changes
Visual C# 2008 Breaking Changes