How do I reinstall/repair the .NET Framework?
The .NET Framework setup sometimes requires a reinstall/repair after you have completed the steps in the On Premises Installation guide to work correctly. (This usually happens if you have installed the .NET Framework before you enable the web role).
Step 1: Reinstall latest version of .NET Framework (e.g. v4.0/4.5) by going to Control panel -> Programs -> Program List -> Microsoft .NET Framework x.x
Step 2: Repair the latest version of .NET framework
Step 3: If this doesn’t resolve the issue, then please try uninstalling and then reinstalling the latest version of the NET. Framework