Added a check to verify that at least .NET Framework 4.5 is installed.

Author: moellerm

Program.cs

@@ -4,12 +4,14 @@ This Source Code Form is subject to the terms of the Mozilla Public
   License, v. 2.0. If a copy of the MPL was not distributed with this
   file, You can obtain one at http://mozilla.org/MPL/2.0/.
  
-  Copyright (C) 2009-2013 Michael Möller <mmoeller@openhardwaremonitor.org>
+  Copyright (C) 2009-2020 Michael Möller <mmoeller@openhardwaremonitor.org>
 	
 */
 
 using System;
 using System.IO;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using System.Threading;
 using System.Windows.Forms;
 using OpenHardwareMonitor.GUI;
@@ -29,7 +31,7 @@ public static void Main() {
           new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException);
       #endif
 
-      if (!AllRequiredFilesAvailable())
+      if (!AllRequiredFilesAvailable() || !IsNetFramework45Installed())
         Environment.Exit(0);
 
       Application.EnableVisualStyles();
@@ -68,6 +70,26 @@ private static bool AllRequiredFilesAvailable() {
       return true;
     }
 
+    private static bool IsNetFramework45Installed() {
+      Type type;      
+      try {
+        type = TryGetDefaultDllImportSearchPathsAttributeType();
+      } catch (TypeLoadException) {
+        MessageBox.Show(
+          "This application requires the .NET Framework 4.5 or a later version.\n" +
+          "Please install the latest .NET Framework. For more information, see\n\n" +
+          "https://dotnet.microsoft.com/download/dotnet-framework",
+          "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
+        return false;
+      }
+      return type != null;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static Type TryGetDefaultDllImportSearchPathsAttributeType() {
+      return typeof(DefaultDllImportSearchPathsAttribute);
+    }
+
     private static void ReportException(Exception e) {
       CrashForm form = new CrashForm();
       form.Exception = e;