AppDomainUnloadedException Class

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

AppDomainUnloadedException.cs

The exception that is thrown when an attempt is made to access an unloaded application domain.

public ref class AppDomainUnloadedException : SystemException

public class AppDomainUnloadedException : SystemException

type AppDomainUnloadedException = class
    inherit SystemException

Public Class AppDomainUnloadedException
Inherits SystemException

Inheritance

Object

Exception

SystemException

AppDomainUnloadedException

Examples

This section contains two code examples. The first example demonstrates the effects of an AppDomainUnloadedException on various threads, and the second shows elementary application domain unloading.

Example 1

The following code example defines a TestClass class that can be marshaled across application domain boundaries and an Example class containing a static (Shared in Visual Basic) ThreadProc method. The ThreadProc method creates an application domain, creates a TestClass object in the domain, and calls a method of TestClass that unloads the executing domain, causing an AppDomainUnloadedException.

The TestClass method is executed without exception handling from a ThreadPool thread and from an ordinary thread, demonstrating that the unhandled exception terminates the task or thread but not the application. It is then executed with and without exception handling from the main application thread, demonstrating that it terminates the application if not handled.

using System;
using System.Threading;
using System.Runtime.InteropServices;

public class Example
{
    public static void Main()
    {
        // 1. Queue ThreadProc as a task for a ThreadPool thread.
        ThreadPool.QueueUserWorkItem(ThreadProc, " from a ThreadPool thread");
        Thread.Sleep(1000);

        // 2. Execute ThreadProc on an ordinary thread.
        Thread t = new Thread(ThreadProc);
        t.Start(" from an ordinary thread");
        t.Join();

        // 3. Execute ThreadProc on the main thread, with
        //    exception handling.
        try
        {
            ThreadProc(" from the main application thread (handled)");
        }
        catch (AppDomainUnloadedException adue)
        {
            Console.WriteLine("Main thread caught AppDomainUnloadedException: {0}", adue.Message);
        }

        // 4. Execute ThreadProc on the main thread without
        //    exception handling.
        ThreadProc(" from the main application thread (unhandled)");

        Console.WriteLine("Main: This message is never displayed.");
    }

    private static void ThreadProc(object state)
    {
        // Create an application domain, and create an instance
        // of TestClass in the application domain. The first
        // parameter of CreateInstanceAndUnwrap is the name of
        // this executable. If you compile the example code using
        // any name other than "Sample.exe", you must change the
        // parameter appropriately.
        AppDomain ad = AppDomain.CreateDomain("TestDomain");
        TestClass tc = (TestClass)ad.CreateInstanceAndUnwrap("Sample", "TestClass");

        // In the new application domain, execute a method that
        // unloads the AppDomain. The unhandled exception this
        // causes ends the current thread.
        tc.UnloadCurrentDomain(state);

        Console.WriteLine("ThreadProc: This message is never displayed.");
    }
}

// TestClass derives from MarshalByRefObject, so it can be marshaled
// across application domain boundaries.
//
public class TestClass : MarshalByRefObject
{
    public void UnloadCurrentDomain(object state)
    {
        Console.WriteLine("\nUnloading the current AppDomain{0}.", state);

        // Unload the current application domain. This causes
        // an AppDomainUnloadedException to be thrown.
        //
        AppDomain.Unload(AppDomain.CurrentDomain);
    }
}

/* This code example produces output similar to the following:
Unloading the current AppDomain from a ThreadPool thread.

Unloading the current AppDomain from an ordinary thread.

Unloading the current AppDomain from the main application thread (handled).
Main thread caught AppDomainUnloadedException: The application domain in which the thread was running has been unloaded.

Unloading the current AppDomain from the main application thread (unhandled).

Unhandled Exception: System.AppDomainUnloadedException: The application domain in which the thread was running has been unloaded.
   at TestClass.UnloadCurrentDomain(Object state)
   at Example.ThreadProc(Object state)
   at Example.Main()
 */

open System
open System.Threading

// TestClass derives from MarshalByRefObject, so it can be marshaled
// across application domain boundaries.
type TestClass() =
    inherit MarshalByRefObject()
    member _.UnloadCurrentDomain (state: obj) =
        printfn $"\nUnloading the current AppDomain{state}."

        // Unload the current application domain. This causes
        // an AppDomainUnloadedException to be thrown.
        //
        AppDomain.Unload AppDomain.CurrentDomain

let threadProc (state: obj) =
    // Create an application domain, and create an instance
    // of TestClass in the application domain. The first
    // parameter of CreateInstanceAndUnwrap is the name of
    // this executable. If you compile the example code using
    // any name other than "Sample.exe", you must change the
    // parameter appropriately.
    let ad = AppDomain.CreateDomain "TestDomain"
    let tc = ad.CreateInstanceAndUnwrap("Sample", "TestClass") :?> TestClass

    // In the new application domain, execute a method that
    // unloads the AppDomain. The unhandled exception this
    // causes ends the current thread.
    tc.UnloadCurrentDomain state

    printfn "ThreadProc: This message is never displayed."

// 1. Queue ThreadProc as a task for a ThreadPool thread.
ThreadPool.QueueUserWorkItem(threadProc, " from a ThreadPool thread") |> ignore
Thread.Sleep 1000

// 2. Execute ThreadProc on an ordinary thread.
let t = Thread(ParameterizedThreadStart threadProc) 
t.Start " from an ordinary thread"
t.Join()

// 3. Execute ThreadProc on the main thread, with
//    exception handling.
try
    threadProc " from the main application thread (handled)"
with :? AppDomainUnloadedException as adue ->
    printfn $"Main thread caught AppDomainUnloadedException: {adue.Message}"

// 4. Execute ThreadProc on the main thread without
//    exception handling.
threadProc " from the main application thread (unhandled)"

printfn "Main: This message is never displayed."

(* This code example produces output similar to the following:
Unloading the current AppDomain from a ThreadPool thread.

Unloading the current AppDomain from an ordinary thread.

Unloading the current AppDomain from the main application thread (handled).
Main thread caught AppDomainUnloadedException: The application domain in which the thread was running has been unloaded.

Unloading the current AppDomain from the main application thread (unhandled).

Unhandled Exception: System.AppDomainUnloadedException: The application domain in which the thread was running has been unloaded.
   at TestClass.UnloadCurrentDomain(Object state)
   at Example.ThreadProc(Object state)
   at Example.main()
 *)

Imports System.Threading
Imports System.Runtime.InteropServices

Public Class Example
    
    Public Shared Sub Main() 

        ' 1. Queue ThreadProc as a task for a ThreadPool thread.
        ThreadPool.QueueUserWorkItem(AddressOf ThreadProc, _
            " from a ThreadPool thread")
        Thread.Sleep(1000)
        
        ' 2. Execute ThreadProc on an ordinary thread.
        Dim t As New Thread(AddressOf ThreadProc)
        t.Start(" from an ordinary thread")
        t.Join()
        
        ' 3. Execute ThreadProc on the main thread, with 
        '    exception handling.
        Try
            ThreadProc(" from the main application thread (handled)")
        Catch adue As AppDomainUnloadedException
            Console.WriteLine("Main thread caught AppDomainUnloadedException: {0}", _
                adue.Message)
        End Try
        
        ' 4. Execute ThreadProc on the main thread without
        '    exception handling.
        ThreadProc(" from the main application thread (unhandled)")
        
        Console.WriteLine("Main: This message is never displayed.")
    
    End Sub 
    
    Private Shared Sub ThreadProc(ByVal state As Object) 
        ' Create an application domain, and create an instance
        ' of TestClass in the application domain. The first
        ' parameter of CreateInstanceAndUnwrap is the name of
        ' this executable. If you compile the example code using
        ' any name other than "Sample.exe", you must change the
        ' parameter appropriately.
        Dim ad As AppDomain = AppDomain.CreateDomain("TestDomain")
        Dim o As Object = ad.CreateInstanceAndUnwrap("Sample", "TestClass")
        Dim tc As TestClass = CType(o, TestClass)
        
        ' In the new application domain, execute a method that
        ' unloads the AppDomain. The unhandled exception this
        ' causes ends the current thread.
        tc.UnloadCurrentDomain(state)
        
        Console.WriteLine("ThreadProc: This message is never displayed.")
    
    End Sub
End Class 

' TestClass derives from MarshalByRefObject, so it can be marshaled
' across application domain boundaries. 
'
Public Class TestClass
    Inherits MarshalByRefObject
    
    Public Sub UnloadCurrentDomain(ByVal state As Object) 
        Console.WriteLine(vbLf & "Unloading the current AppDomain{0}.", state)
        
        ' Unload the current application domain. This causes
        ' an AppDomainUnloadedException to be thrown.
        '
        AppDomain.Unload(AppDomain.CurrentDomain)
    
    End Sub 
End Class 

' This code example produces output similar to the following:
'
'Unloading the current AppDomain from a ThreadPool thread.
'
'Unloading the current AppDomain from an ordinary thread.
'
'Unloading the current AppDomain from the main application thread (handled).
'Main thread caught AppDomainUnloadedException: The application domain in which the thread was running has been unloaded.
'
'Unloading the current AppDomain from the main application thread (unhandled).
'
'Unhandled Exception: System.AppDomainUnloadedException: The application domain in which the thread was running has been unloaded.
'   at TestClass.UnloadCurrentDomain(Object state)
'   at Example.ThreadProc(Object state)
'   at Example.Main()
'

Example 2

The following code example creates and unloads an application domain, and demonstrates that an AppDomainUnloadedException is thrown on a subsequent attempt to access the unloaded 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 the .NET Framework version 2.0, an AppDomainUnloadedException that is not handled in user code has the following effect:

• If a thread was started in managed code, it is terminated. The unhandled exception is not allowed to terminate the application.

• If a task is executing on a ThreadPool thread, it is terminated and the thread is returned to the thread pool. The unhandled exception is not allowed to terminate the application.

• If a thread started in unmanaged code, such as the main application thread, it is terminated. The unhandled exception is allowed to proceed, and the operating system terminates the application.

AppDomainUnloadedException uses the HRESULT COR_E_APPDOMAINUNLOADED, which has the value 0x80131014.

For a list of initial property values for an instance of AppDomainUnloadedException, see the AppDomainUnloadedException constructors.

Constructors

AppDomainUnloadedException()	Initializes a new instance of the AppDomainUnloadedException class.
AppDomainUnloadedException(SerializationInfo, StreamingContext)	Obsolete. Initializes a new instance of the AppDomainUnloadedException class with serialized data.
AppDomainUnloadedException(String)	Initializes a new instance of the AppDomainUnloadedException class with a specified error message.
AppDomainUnloadedException(String, Exception)	Initializes a new instance of the AppDomainUnloadedException class with a specified error message and a reference to the inner exception that is the cause of this exception.

Properties

Data	Gets a collection of key/value pairs that provide additional user-defined information about the exception. (Inherited from Exception)
HelpLink	Gets or sets a link to the help file associated with this exception. (Inherited from Exception)
HResult	Gets or sets HRESULT, a coded numerical value that is assigned to a specific exception. (Inherited from Exception)
InnerException	Gets the Exception instance that caused the current exception. (Inherited from Exception)
Message	Gets a message that describes the current exception. (Inherited from Exception)
Source	Gets or sets the name of the application or the object that causes the error. (Inherited from Exception)
StackTrace	Gets a string representation of the immediate frames on the call stack. (Inherited from Exception)
TargetSite	Gets the method that throws the current exception. (Inherited from Exception)

Methods

Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetBaseException()	When overridden in a derived class, returns the Exception that is the root cause of one or more subsequent exceptions. (Inherited from Exception)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetObjectData(SerializationInfo, StreamingContext)	Obsolete. When overridden in a derived class, sets the SerializationInfo with information about the exception. (Inherited from Exception)
GetType()	Gets the runtime type of the current instance. (Inherited from Exception)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Creates and returns a string representation of the current exception. (Inherited from Exception)

Events

SerializeObjectState

Obsolete. Occurs when an exception is serialized to create an exception state object that contains serialized data about the exception. (Inherited from Exception)

See also

• AppDomain
• Exception
• Handling and throwing exceptions in .NET