.NET Framework Developer Center: Compatibility Testing Scenarios

.NET Framework Developer Center: Compatibility Testing Scenarios: "This document outlines best practices for testing a managed application or component for compatibility with newer runtime versions. It covers different configurations you should test to ensure that the application continues to run properly. Full details on compatibility are available in Microsoft .NET Framework 1.1 and 2.0 (Beta) Compatibility. If you have not already read that document, we recommend that you read that before proceeding.
Summary

Many applications using managed code require that a particular version of the .NET Framework be present on the machine. Some applications redistribute a particular release of the.NET Framework. In some cases, applications that were developed on a specific version of the .NET Framework may encounter issues when trying to execute on a newer version of the Framework. As explained in Microsoft .NET Framework 1.1 and 2.0 (Beta) Compatibility, managed applications run by default on the version of the Framework they were built against. However, in certain situations where only a newer version of the Framework is available or a hosting application requires a particular version, an application may run against a newer version. To ensure the best customer experience, we recommend that you test your applications for compatibility according to the steps described below."