visual studio - Microsoft .NET compatibility

Question

I used VS2010, and target for .Net 2.0 (VB.Net Windows Form application)

How to decide what is the .Net target I decided on 2.0 because I understood it will be OK if the users have higher version

I tested my app on XP with .Net 2.0, works fine.

I uninstalled .Net 2.0 [to see what error message users might get]

[a few files were still left in C:WindowsMicrosoft.NetFrameworkv2.0.50727 but not all files]

I installed .Net 4 [. . . also needed to install Windows Installer 3.1, and Windows Imaging Component, as pre-requirments . . .]

but now when I run my app I get the error - "unable to find a version of the runtime to run this application"

so what should I recomend my clients? to install 2.0?

Thanks,

Atara

Update: I am going to recommend my XP users to install .Net 3.5 SP1

Answer 1

A .NET 2.0 application needs .NET 2.0 to run. A .NET 3.0 or 3.5 application only needs .NET 2.0 plus whatever additional .NEt 3.0/3.5 assemblies it actually uses.

A .NET 4.0 application needs the .NET 4.0 CLR, so .NET 4.0 must be installed.