Breaking changes in .NET 4.0

Question

There is a lot of information about new features and classes in new 4.0 however there are also changes that may affect existing applications, for example

1. Ti

Answer 1

The languages documentation team publishes separate documents for C# and VB breaking changes:

VB: http://msdn.microsoft.com/en-us/library/cc714070%28VS.100%29.aspx

C#: http://msdn.microsoft.com/en-us/library/ee855831%28VS.100%29.aspx

I wrote the C# one and included covariance and contravariance breaking changes mentioned by Eric Lippert, and events changes discussed by Chris Burrows. There are also some breaking changes around optional parameters, embedded interop types, and method group type inference.

Update:

One more useful document (from .NET documentation team): http://msdn.microsoft.com/en-us/library/ee941656%28VS.100%29.aspx