Which release should I install?

Since the original release of .NET 4.0.0 in April 2010 there have been multiple updates. By Dec 2011 the current release was 4.0.3.xxxx and this was the only release available on the download center.

In Visual Studio if you target .NET 4 your code will run on .NET 4.0.0 or higher.
If you target .NET 4 Platform update 1 your code will run on .NET 4.0.1 or higher.

If you install .NET 4 in December 2011 or later you will get .NET 4.0.3 so either release will work.

If you install with NuGet you will get both releases.

Last edited Dec 9, 2011 at 5:05 PM by ronjacobs, version 1

Comments

Suncat2000 Aug 23, 2012 at 5:53 PM 
Warning. If you compile against the 4.5 release in your project, and you don't have the .NET 4.5 Framework installed at runtime, your program will eventually fail with the following exception: System.TypeLoadException: Could not load type 'System.Runtime.CompilerServices.ExtensionAttribute' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. This is because .NET 4.5 makes subtle breaking changes to the framework. If you're going to run on a machine with .NET 4.0 - save yourself a couple days of frustration - DO NOT compile against version 4.5 of this (or any other) library. Ouch!