check which .net framework installed on machine

create console app .net framework 4.8 for this.

using Microsoft.Win32;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace check_net_framework
{
    class Program
    {
        static void Main(string[] args)
        {
            const string subkey = @"SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full\";

            using (var ndpKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32).OpenSubKey(subkey))
            {
                if (ndpKey != null && ndpKey.GetValue("Release") != null)
                {
                    Console.WriteLine($".NET Framework Version: {CheckFor45PlusVersion((int)ndpKey.GetValue("Release"))}");
                }
                else
                {
                    Console.WriteLine(".NET Framework Version 4.5 or later is not detected.");
                }
            }
            
            // Checking the version using >= enables forward compatibility.
            string CheckFor45PlusVersion(int releaseKey)
            {
                if (releaseKey >= 528040)
                    return "4.8 or later";
                if (releaseKey >= 461808)
                    return "4.7.2";
                if (releaseKey >= 461308)
                    return "4.7.1";
                if (releaseKey >= 460798)
                    return "4.7";
                if (releaseKey >= 394802)
                    return "4.6.2";
                if (releaseKey >= 394254)
                    return "4.6.1";
                if (releaseKey >= 393295)
                    return "4.6";
                if (releaseKey >= 379893)
                    return "4.5.2";
                if (releaseKey >= 378675)
                    return "4.5.1";
                if (releaseKey >= 378389)
                    return "4.5";
                // This code should never execute. A non-null release key should mean
                // that 4.5 or later is installed.
                return "No 4.5 or later version detected";
            }

            Console.ReadLine();
        }
    }
}

IIS ApplicationPoolIdentity does not have write permission to 'Temporary ASP.NET Files'

 

1. Open a Command window as an administrator (Start / Programs / Accessories, then right-click over Command Prompt, then choose "Run as administrator").

2. Enter the following command:

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

Substitute your domain and user for domain\user in the example above. That's all it took.