Apr 4, 2020

Failed to install Intel HAXM

When installing Android SDK Platform-Tools on Windows you may see following error:

Running Intel® HAXM installer Failed to install Intel HAXM. 
For details, please check the installation log: HAXM installation failed. To install HAXM follow the instructions found at:
This computer does not support Intel Virtualization Technology (VT-x)
or it is being exclusively used by Hyper-V.
HAXM cannot be installed. Please ensure Hyper-V is disabled in Windows Features,
or refer to the Intel HAXM documentation for more information.
I will list 3 different options.

1. Program and Features

Be sure Hyper-V not marked. If installed uncheck it.

2. Command line (CMD)

dism.exe /Online /Disable-Feature:Microsoft-Hyper-V
bcdedit /set hypervisorlaunchtype off

3. Device Guard and Credential Guard hardware readiness tool

Download tool, unzip and open powershell window.

First change execution policy.
PS C:\temp\dgreadiness_v3.6> set-executionpolicy remotesigned 
Execution Policy Change The execution policy helps protect you from scripts that you do not trust.
Changing the execution policy might expose you to the security risks described in the about_Execution_Policies help topic at https:/go.microsoft.com/fwlink/?LinkID=135170.
Do you want to change the execution policy? [Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default is "N"): a
Run command.
PS C:\temp\dgreadiness_v3.6> .\DG_Readiness_Tool_v3.6.ps1 -Disable 
Do you want to run software from this untrusted publisher?
File C:\temp\dgreadiness_v3.6\DG_Readiness_Tool_v3.6.ps1 is published by CN=Microsoft Corporation, O=Microsoft Corporation, L=Redmond, S=Washington, C=US and is not trusted on your system. Only run scripts from trusted publishers.
[V] Never run [D] Do not run [R] Run once [A] Always run [?] Help (default is "D"): a
You will see success messages.
Disabling Hyper-V and IOMMU
Disabling Hyper-V and IOMMU successful
Please reboot the machine, for settings to be applied.
After reboot continue to install HAXM.

Mar 16, 2020

Dynamic Assembly Loading (C# Reflection)

We will achieve following task with dynamic assembly loading in C#.

using System.Net.Http;
using System;
using System.Linq;

var client = new HttpClient();
client.BaseAddress = new Uri("http://api.open-notify.org/astros.json");
string result = client.GetStringAsync("").Result;

Don't add System.Net.Http dll to your reference list. It will be automatically loaded from GAC.

using System;
using System.Linq;
using System.Reflection;

//We don't have "using System.Net.Http" 

//Load System.Net.Http
string name1 = "System.Net.Http,Version=," + "Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a";
Assembly a1 = Assembly.Load(name1);

//Create HttpClient instance
Type clientType = a1.GetTypes().Where(t => t.Name.Equals("HttpClient")).Single();
object client = Activator.CreateInstance(clientType);

//Set BaseAddress on client
PropertyInfo propertyBaseAddress = clientType.GetProperties().Where(p => p.Name == "BaseAddress").Single();
Uri url = new Uri("http://api.open-notify.org/astros.json");
propertyBaseAddress.SetValue(client, url);

//Test property value
var BaseAddressValue = propertyBaseAddress.GetValue(client);

//Get HttpResponseMessage Task
var methodGetStringAsync = clientType.GetMethod("GetStringAsync", new Type[] { typeof(Uri) });
var responseTask = methodGetStringAsync.Invoke(client, new string[] { null });

//Get HttpResponseMessage result from Task
var responseType = responseTask.GetType();
PropertyInfo propResponse = responseType.GetProperties().Where(p => p.Name == "Result").Single();

var responseResult = propResponse.GetValue(responseTask);  //This is the string result

Bonus: List your loaded assemblies

Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies();

foreach (Assembly a in assemblies)

mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089 System.Core, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089 System, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089 System.Net.Http, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a System.Configuration, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a System.Xml, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089
System.Net.Http is displayed here even not referenced in Visual Studio.

Mar 13, 2020

Strong Name Signing in .NET

Using a strong name protects your assembly against manipulation.

For example your software using a class named Class1 in ClassLibrary1 namespace.

If you compile a new dll contains ClassLibrary1.Class1 then you can use this dll instead of original one.

This is very basic example but it can be applicable in real life.

To be sure that your software is using your assembly version then you can sign your project.

Microsoft description is:
When a strong-named assembly is created, it contains the simple text name of the assembly, the version number, optional culture information, a digital signature, and the public key that corresponds to the private key used for signing.
Example here shows signing process in Visual Studio. You can use also command line tool (sn.exe).


Our solution has 2 projects, executable and a class library. Main program is using ClassLibrary1.Class1

using ClassLibrary1;
using System;

namespace strongname
    class Program
        static void Main(string[] args)
            Console.WriteLine("strongname loaded");

            Class1 c = new Class1();


using System;

namespace ClassLibrary1
    public class Class1
        public Class1()
            Console.WriteLine("Hello from Class1");


Right click to project in VS and select Properties. In Signing tab check "Sign the assembly" and select "New" in listbox. Enter password for your private key.

This will create a pfx (Personal Information Exchange Format) file in your project folder.


strongname loaded
Hello from Class1


If you create a new project with the same namespace, class and functions then you can use the new dll with current executable.

For test change the code and recompile dll in outside of project folder.

csc.exe /t:library /out:ClassLibrary1.dll Class1.cs
Then replace the old ClassLibrary1.dll with the new file.


When you try to run your executable an error will be shown because the new dll has not signed with correct key.


Unhandled Exception: System.IO.FileLoadException: Could not load file or assembly 'ClassLibrary1, Version=, Culture=neutral, PublicKeyToken=77d705841860f240' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
at strongname.Program.Main(String[] args)

If you completely remove signing from your projects then your manipulated dll will work.

Jan 7, 2020

Asp.Net Settings for Hosting

1. Security Exception

Description: The application attempted to perform an operation not allowed by the security policy.To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.

Exception Details: System.Security.SecurityException: Request failed.


   <trust level="Full" />

2. Publish website without roslyn

Uninstall-package Microsoft.CodeDom.Providers.DotNetCompilerPlatform "Your Web API project name"
In your publish profile settings, uncheck "Allow precompiled site to be updatable". You can find this under Settings > Precompile during publishing > configure.

Remove codedom from web.config.
      <compiler language="c#;cs;csharp" extension=".cs"
        type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
        warningLevel="4" compilerOptions="/langversion:6 /nowarn:1659;1699;1701"/>
      <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb"
        type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
        warningLevel="4" compilerOptions="/langversion:14 /nowarn:41008 /define:_MYTYPE=\"Web\" /optionInfer+"/>

4. MapPath


4. Restrict file download

Create web.config file in the folder you want to prevent file download for a specific extension.
<?xml version="1.0" encoding="UTF-8"?>
                <fileExtensions applyToWebDAV="false">
                     <add fileExtension=".txt" allowed="false" />