List of Breaking Changes
Please review this document that describes all the known changes in the .NET Framework 2.0 that might impact an application that targeted the .NET Framework 1.1. All changes were carefully documented and reviewed. For a complete description of compatibility testing and how to test your applications, please see the white paper titled Microsoft .NET Framework 1.1 and 2.0 Compatibility.
Breaking changes are changes in either the .NET Framework (runtime breaking changes) or Visual Studio (design/compile/project upgrade) that make certain application and development scenarios behave differently. These are not necessarily changes that we have found to impact an application, rather these are changes in behavior discovered during design review and testing that could potentially impact an application.
Runtime changes can be classified into two categories: The first (and rarest) is an API breaking change where the signature of a function changed or a function was removed. In almost all cases these changes were made due to security concerns. The second, more common type of breaking change is a behavior breaking change where the behavior of a method changed. Examples of this type of change include changing the exception thrown due to a particular error or increasing the precision of floating point operations.
If you believe that your application is being impacted by a change not documented on this list, please follow the steps outlined in Microsoft .NET Framework 1.1 and 2.0 Compatibility to report the change.