Use the ASP.NET IIS Registration Tool (aspnet_regiis.exe,) to register ASP.NET 4.0.
1. Open a Command Prompt window as an administrator, as follows:
a. From the Start menu, click All Programs, and then Accessories.
b. Right-click Command Prompt and then choose Run as administrator.
2. Change directory to the Microsoft.NET\Framework\v4.0.30319 folder. For example if the folder is on drive C:, enter the following command:
cd C: \Windows\Microsoft.NET\Framework\v4.0.30319
aspnet_regiis.exe -iru and then press Enter. iisreset and then press Enter.