AppDomain.Unload(AppDomain) Method

Reference

Definition

Namespace:: System

Assemblies:: netstandard.dll, System.Runtime.dll

Assembly:: System.Runtime.Extensions.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: AppDomain.cs

Source:: AppDomain.cs

Source:: AppDomain.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Caution

Creating and unloading AppDomains is not supported and throws an exception.

Unloads the specified application domain.

public:
 static void Unload(AppDomain ^ domain);

public static void Unload(AppDomain domain);

[System.Obsolete("Creating and unloading AppDomains is not supported and throws an exception.", DiagnosticId="SYSLIB0024", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
public static void Unload(AppDomain domain);

static member Unload : AppDomain -> unit

[<System.Obsolete("Creating and unloading AppDomains is not supported and throws an exception.", DiagnosticId="SYSLIB0024", UrlFormat="https://aka.ms/dotnet-warnings/{0}")>]
static member Unload : AppDomain -> unit

Public Shared Sub Unload (domain As AppDomain)

Parameters

domain: AppDomain

An application domain to unload.

Attributes: ObsoleteAttribute

Exceptions

ArgumentNullException

domain is null.

CannotUnloadAppDomainException

.NET Core and .NET 5+ only: In all cases.

-or-

domain could not be unloaded.

Exception

An error occurred during the unload process.

Examples

The following code example shows how to unload an application domain.

using namespace System;
using namespace System::Reflection;
using namespace System::Security::Policy;

//for evidence Object*
int main()
{
   
   //Create evidence for the new appdomain.
   Evidence^ adevidence = AppDomain::CurrentDomain->Evidence;
   
   // Create the new application domain.
   AppDomain^ domain = AppDomain::CreateDomain( "MyDomain", adevidence );
   Console::WriteLine( "Host domain: {0}", AppDomain::CurrentDomain->FriendlyName );
   Console::WriteLine( "child domain: {0}", domain->FriendlyName );
   
   // Unload the application domain.
   AppDomain::Unload( domain );
   try
   {
      Console::WriteLine();
      
      // Note that the following statement creates an exception because the domain no longer exists.
      Console::WriteLine( "child domain: {0}", domain->FriendlyName );
   }
   catch ( AppDomainUnloadedException^ /*e*/ ) 
   {
      Console::WriteLine( "The appdomain MyDomain does not exist." );
   }

}

using System;
using System.Reflection;
using System.Security.Policy;
class ADUnload
{
    public static void Main()
    {

        //Create evidence for the new appdomain.
        Evidence adevidence = AppDomain.CurrentDomain.Evidence;

        // Create the new application domain.
        AppDomain domain = AppDomain.CreateDomain("MyDomain", adevidence);

                Console.WriteLine("Host domain: " + AppDomain.CurrentDomain.FriendlyName);
                Console.WriteLine("child domain: " + domain.FriendlyName);
        // Unload the application domain.
        AppDomain.Unload(domain);

        try
        {
        Console.WriteLine();
        // Note that the following statement creates an exception because the domain no longer exists.
                Console.WriteLine("child domain: " + domain.FriendlyName);
        }

        catch (AppDomainUnloadedException e)
        {
        Console.WriteLine("The appdomain MyDomain does not exist.");
        }
    }
}

open System

//Create evidence for the new appdomain.
let adevidence = AppDomain.CurrentDomain.Evidence

// Create the new application domain.
let domain = AppDomain.CreateDomain("MyDomain", adevidence)

printfn $"Host domain: {AppDomain.CurrentDomain.FriendlyName}"
printfn $"child domain: {domain.FriendlyName}"
// Unload the application domain.
AppDomain.Unload domain

try
    printfn ""
    // Note that the following statement creates an exception because the domain no longer exists.
    printfn $"child domain: {domain.FriendlyName}"

with :? AppDomainUnloadedException ->
    printfn "The appdomain MyDomain does not exist."

Imports System.Reflection
Imports System.Security.Policy

Class ADUnload
   
   Public Shared Sub Main()

      'Create evidence for the new appdomain.
      Dim adevidence As Evidence = AppDomain.CurrentDomain.Evidence

      ' Create the new application domain.
      Dim domain As AppDomain = AppDomain.CreateDomain("MyDomain", adevidence)
      
      Console.WriteLine(("Host domain: " + AppDomain.CurrentDomain.FriendlyName))
      Console.WriteLine(("child domain: " + domain.FriendlyName))
      ' Unload the application domain.
      AppDomain.Unload(domain)
      
      Try
         Console.WriteLine()
         ' Note that the following statement creates an exception because the domain no longer exists.
         Console.WriteLine(("child domain: " + domain.FriendlyName))
      
      Catch e As AppDomainUnloadedException
         Console.WriteLine("The appdomain MyDomain does not exist.")
      End Try
   End Sub
End Class

Remarks

In .NET Framework version 2.0 and later, there is a thread dedicated to unloading application domains. This improves reliability, especially when .NET Framework is hosted. When a thread calls Unload, the target domain is marked for unloading. The dedicated thread attempts to unload the domain, and all threads in the domain are aborted. If a thread does not abort, for example because it is executing unmanaged code, or because it is executing a finally block, then after a period of time, a CannotUnloadAppDomainException is thrown in the thread that originally called Unload. If the thread that could not be aborted eventually ends, the target domain is not unloaded. Thus, in .NET Framework version 2.0 and later, domain is not guaranteed to unload, because it might not be possible to terminate executing threads.

Note

In some cases, calling Unload causes an immediate CannotUnloadAppDomainException, for example if it is called in a finalizer.

The threads in domain are terminated using the Abort method, which throws a ThreadAbortException in the thread. Although the thread should terminate promptly, it can continue executing for an unpredictable amount of time in a finally clause.

Applies to

Product	Versions (Obsolete)
.NET	Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5 (6, 7, 8, 9)
.NET Framework	1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	2.0, 2.1

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