6 Comments

• .NET 2.0 and above are not compatible with .NET 1.1 (or previous editions).
  
  .NET 3.0 and 3.5 build on 2.0 (2.0 is the core).
  

• This is the way it is supposed to be.
  
  .Net 1.0, 1.1 => CLR version 1.0
  .Net 2.0, 3.0, 3.5 => CLR Version 2.0
  
  So that means, if you install 1.1, you will not need to install 1.0 or if you install 3.5, you don't need to install 2.0, but 1.1 and 3.5 are different CLR versions.
  
  I hope you get the idea. :)
  
  Yogesh.
  

• Suresh, the .Net Framework 3.0 and 3.5 are actually just the .Net Framework 2.0 with some additional features. This means that any app that runs with .Net 2.0 will be 100% compatible with 3.0 and 3.5. However, this is not the case for 1.1. The 2.0 release saw a lot of modifications in the framework itself so that applications built for the 1.1 framework do not run on the 2.0 framework. It is possible to build an older app on the 2.0 framework however but there is no garantee that you wouldn't have to make some adjustments for the build to succeed.
  So, in short, even if you have the 2.0, 3.0 and/or 3.5 frameworks installed, you won't be able to run an application built for 1.1
  
  Hope this answers your question
  

• .NET applications can require a particular version of .NET. This app apparently does so.
  

• @benoit808: Not entirely true! There are breaking changes in 3.5 SP1!
  
  As 3.5 is not really part of the .net framework but more additionaly libraries.
  
  You *can* run .net 2.0 applications on 1.1 with the correct .config file but most installers check for availability of certain registry values. The reason not to use installers and just do xcopy based deployments.
  

• Greats inputs,thanks a lot.I did not know this...
  Suresh