We are considering to change our present .net2 on IIS6 server to .net4 (or 4.5). Can someone help us with some basics about this?
After we install .net4 to our production IIS. Is every .net site defaulting to .net4? we have had some dificulties with 64-bit version so we have forced IIS6 to run in 32-bit mode. Does update do something to this? After installing .net4, how can we force specific application pool to operate on .net2 mode and on 32.bit mode?
What problems there might come out on transforming .net2 sites directly to .net 4 sites? Or is there any?
It's been a while since I've last used .NET, but here's my general suggestion.
First, Migrate to .NET 4! .NET 4 offers better security and new features. Consider that as your first option.
Second, in my experience, if you have multiple versions of framework installed on the server, you should be able to choose which version to operate that site.
Lastly, I'm not sure about 32/64 bit thing, but my suggestion is to simply fix it! Applications, especially heavy-load applications can operate better in 64-bit mode.
Make you application as future-proof as possible!
As for what problems you might run into, I really depends on what kind of APIs you're using, chances are, they will be a few deprecated methods, properties. Also, look at some new features, there might be new APIs worth trying, try that at a development server, it might increase overall user experience and even application performance.
Good luck!