This documentation is archived and is not being maintained.

AppDomain.Load Method (Byte[], Byte[])

Updated: March 2011

Loads the Assembly with a common object file format (COFF) based image containing an emitted Assembly. The raw bytes representing the symbols for the Assembly are also loaded.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public Assembly Load(
	byte[] rawAssembly,
	byte[] rawSymbolStore


Type: System.Byte[]

An array of type byte that is a COFF-based image containing an emitted assembly.

Type: System.Byte[]

An array of type byte containing the raw bytes representing the symbols for the assembly.

Return Value

Type: System.Reflection.Assembly
The loaded assembly.


_AppDomain.Load(Byte[], Byte[])


rawAssembly is null.


rawAssembly is not a valid assembly.


Version 2.0 or later of the common language runtime is currently loaded and rawAssembly was compiled with a later version.


The operation is attempted on an unloaded application domain.


An assembly or module was loaded twice with two different evidences.

This method should be used only to load an assembly into the current application domain. This method is provided as a convenience for interoperability callers who cannot call the static Assembly.Load method. To load assemblies into other application domains, use a method such as CreateInstanceAndUnwrap.

For information that is common to all overloads of this method, see the Load(AssemblyName) method overload.

The following example demonstrates the use of loading a raw assembly.

For this code example to run, you must provide the fully qualified assembly name. For information about how to obtain the fully qualified assembly name, see Assembly Names.

using System;
using System.IO;
using System.Reflection;
using System.Reflection.Emit;

class Test {
   public static void Main() {
      AppDomain currentDomain = AppDomain.CurrentDomain;

      InstantiateMyType(currentDomain);   // Failed!

      currentDomain.AssemblyResolve += new ResolveEventHandler(MyResolver);

      InstantiateMyType(currentDomain);   // OK!

   static void InstantiateMyType(AppDomain domain) {
      try {
	 // You must supply a valid fully qualified assembly name here.
         domain.CreateInstance("Assembly text name, Version, Culture, PublicKeyToken", "MyType");
      } catch (Exception e) {

   // Loads the content of a file to a byte array.  
   static byte[] loadFile(string filename) {
      FileStream fs = new FileStream(filename, FileMode.Open);
      byte[] buffer = new byte[(int) fs.Length];
      fs.Read(buffer, 0, buffer.Length);

      return buffer;

   static Assembly MyResolver(object sender, ResolveEventArgs args) {
      AppDomain domain = (AppDomain) sender;

      // Once the files are generated, this call is 
      // actually no longer necessary.

      byte[] rawAssembly = loadFile("temp.dll");
      byte[] rawSymbolStore = loadFile("temp.pdb");
      Assembly assembly = domain.Load(rawAssembly, rawSymbolStore);

      return assembly;

   // Creates a dynamic assembly with symbol information 
   // and saves them to temp.dll and temp.pdb 
   static void EmitAssembly(AppDomain domain) {
      AssemblyName assemblyName = new AssemblyName();
      assemblyName.Name = "MyAssembly";

      AssemblyBuilder assemblyBuilder = domain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Save);
      ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("MyModule", "temp.dll", true);
      TypeBuilder typeBuilder = moduleBuilder.DefineType("MyType", TypeAttributes.Public);

      ConstructorBuilder constructorBuilder = typeBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, null);
      ILGenerator ilGenerator = constructorBuilder.GetILGenerator();
      ilGenerator.EmitWriteLine("MyType instantiated!");



Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0




March 2011

Clarified that this method is not for loading assemblies into other application domains.

Customer feedback.