ObjectDisposedException Class (System) (original) (raw)

Definition

The exception that is thrown when an operation is performed on a disposed object.

public ref class ObjectDisposedException : InvalidOperationException

public class ObjectDisposedException : InvalidOperationException

[System.Serializable]
public class ObjectDisposedException : InvalidOperationException

[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public class ObjectDisposedException : InvalidOperationException

type ObjectDisposedException = class
    inherit InvalidOperationException

[<System.Serializable>]
type ObjectDisposedException = class
    inherit InvalidOperationException

[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type ObjectDisposedException = class
    inherit InvalidOperationException

Public Class ObjectDisposedException
Inherits InvalidOperationException

Inheritance

Inheritance

Attributes

Examples

The following example demonstrates an error that causes the ObjectDisposedException exception to be thrown.

using System;
using System.IO;

public class ObjectDisposedExceptionTest
{
   public static void Main()
   {
      MemoryStream ms = new MemoryStream(16);
      ms.Close();
      try
      {
         ms.ReadByte();
      }
      catch (ObjectDisposedException e)
      {
         Console.WriteLine("Caught: {0}", e.Message);
      }
   }
}

open System
open System.IO

let ms = new MemoryStream 16
ms.Close()
try
    ms.ReadByte()
    |> ignore
with :? ObjectDisposedException as e ->
   printfn $"Caught: {e.Message}"

Imports System.IO

Public Class ObjectDisposedExceptionTest
   
   Public Shared Sub Main()
      Dim ms As New MemoryStream(16)
      ms.Close()
      Try
         ms.ReadByte()
      Catch e As ObjectDisposedException
         Console.WriteLine("Caught: {0}", e.Message)
      End Try
   End Sub
End Class

This code produces the following output:

Caught:
  Cannot access a closed Stream.

An ObjectDisposedException is thrown when you try to access a member of an object that implements the IDisposable interface or IAsyncDisposable interface, and that object has been disposed. Typically, this exception is caused by one of the following conditions:

• You've called an IDisposable object's Dispose method (or an IDisposableAsync object's DisposeAsync method), and you're trying to access an instance member that gets or sets the object's state. The following example illustrates the ObjectDisposedException that is thrown when you try to reset the frequency of timer notifications after you call the Timer.Dispose method.

using System;  
using System.Threading;  
public class Example  
{  
   public static void Main()  
   {  
      Timer t = new Timer(TimerNotification, null,  
                         100, Timeout.Infinite);  
      Thread.Sleep(2000);  
      t.Dispose();  
      t.Change(200, 1000);  
      Thread.Sleep(3000);  
   }  
   private static void TimerNotification(Object obj)  
   {  
      Console.WriteLine("Timer event fired at {0:F}", DateTime.Now);  
   }  
}  
// The example displays output like the following:  
//    Timer event fired at Monday, July 14, 2014 11:54:08 AM  
//  
//    Unhandled Exception: System.ObjectDisposedException: Cannot access a disposed object.  
//       at System.Threading.TimerQueueTimer.Change(UInt32 dueTime, UInt32 period)  
//       at Example.Main()  

open System  
open System.Threading  
let timerNotification _ =  
    printfn $"Timer event fired at {DateTime.Now:F}"  
let t = new Timer(timerNotification, null, 100, Timeout.Infinite)  
Thread.Sleep 2000  
t.Dispose()  
t.Change(200, 1000)  
|> ignore  
Thread.Sleep 3000  
// The example displays output like the following:  
//    Timer event fired at Monday, July 14, 2014 11:54:08 AM  
//  
//    Unhandled Exception: System.ObjectDisposedException: Cannot access a disposed object.  
//       at System.Threading.TimerQueueTimer.Change(UInt32 dueTime, UInt32 period)  
//       at <StartupCode$fs>.main()  

Imports System.Threading  
Module Example  
   Public Sub Main()  
      Dim t As New Timer(AddressOf TimerNotification, Nothing,  
                         100, Timeout.Infinite)  
      Thread.Sleep(2000)  
      t.Dispose()  
        
      t.Change(200, 1000)  
      Thread.Sleep(3000)  
   End Sub  
   Private Sub TimerNotification(obj As Object)  
      Console.WriteLine("Timer event fired at {0:F}", Date.Now)  
   End Sub  
End Module  
' The example displays output like the following:  
'    Timer event fired at Monday, July 14, 2014 11:54:08 AM  
'  
'    Unhandled Exception: System.ObjectDisposedException: Cannot access a disposed object.  
'       at System.Threading.TimerQueueTimer.Change(UInt32 dueTime, UInt32 period)  
'       at Example.Main()  

• You've called an object's Close method, and you're trying to access an instance member that gets or sets the object's state. Often, the Close method provides a type's public implementation of the IDisposable.Dispose method. The same is true for CloseAsync and <xref:System.IAsyncDisposable.DisposeAsync%2A?displayProperty=nameWithType>.
• You've called an object's Dispose or DisposeAsync methods multiple times. Typically, this doesn't throw an exception. However, depending on how a type implements IDisposable.Dispose or IAsyncDisposable.DisposeAsync, it may not allow multiple calls to that method.

In most cases, this exception results from developer error. Instead of handling the error in a try/catch block, you should correct the error, typically by reinstantiating the object.

Applies to

See also

• IDisposable