How to find out if .NET 3.5 SP1 is installed?
If you can go to the "Add or Remove Programs" on the control panel, it should be indicated in the "
Microsoft ASP.Net xxx
I have a version number 1.0.20105.0 in the control panel, which is at least 4.0.
You can also go to "IIS" → "Application Pools" → Click "DefaultAppPool" and select "Basic Settings"; then in the ".NET Framework Version:" section, see if there is a ".Net Framework v.4x"