Open a command window as “administrator” and run: C:\WIndows\Microsoft.NET\Framework64\v2.0.50727\Aspnet_regiis.exe -ga server\user

and or

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Aspnet_regiis.exe -ga server\user

For example:

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Aspnet_regiis.exe -ga 111admin333