During a recent attempt to install a .NET application, I encountered a horrible thing … The installation was bombing out without a good, descriptive error. After banging my head against and doing some amazing google/bing ninja moves, I discovered that this was in fact a ‘feature’ and not a bug related to the backwards compatibility of .NET 4.0 and there not being any other version of the .NET Framework installed.
.NET 4.0 Framework is not natively backward compatible with applications written for previous version of the .NET Framework. So if you’re a developer and are looking for a quick fix, try adding this line to the application config file.
If you’d like to learn more about .NET Framework comparability, check out these links to the MSDN Library: Version Compatibility in the .NET Framework & .NET Framework 4 RTM Application Compatibility Walkthrough/