Export (0) Print
Expand All
Expand Minimize

UnhandledExceptionMode Enumeration

Defines where a Windows Forms application should send unhandled exceptions.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public enum class UnhandledExceptionMode

Member nameDescription
AutomaticRoute all exceptions to the ThreadException handler, unless the application's configuration file specifies otherwise.
CatchExceptionAlways route exceptions to the ThreadException handler. Ignore the application configuration file.
ThrowExceptionNever route exceptions to the ThreadException handler. Ignore the application configuration file.

This enumeration is used by SetUnhandledExceptionMode.

NoteNote

In the .NET Framework version 2.0, the common language runtime behavior changed to allow unhandled exceptions to propagate up the call stack. This behavior can be disabled via the application configuration file. For more information, see Exceptions in Managed Threads.

The following code example sets event handlers for both errors that occur on Windows Forms threads and errors that occur on other threads. It sets SetUnhandledExceptionMode so that all errors are handled by the application, regardless of the settings in the application's user configuration file. It uses the ThreadException event for the former, and the UnhandledException event for the latter. Since UnhandledException cannot prevent an application from terminating, the example simply logs the error in the system Event Log prior to termination.

This sample assumes that you have defined two Button controls, button1 and button2, on your Form class.

   // Creates a class to throw the error. 
public:
   ref class ErrorHandler: public System::Windows::Forms::Form
   {
      // Inserts the code to create a form with a button. 

      // Programs the button to throw an exception when clicked. 
   private:
      void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
      {
         throw gcnew ArgumentException( "The parameter was invalid" );
      }

   public:
      static void Main()
      {
         // Creates an instance of the methods that will handle the exception.
         CustomExceptionHandler ^ eh = gcnew CustomExceptionHandler;

         // Adds the event handler to to the event.
         Application::ThreadException += gcnew ThreadExceptionEventHandler( eh, &Form1::CustomExceptionHandler::OnThreadException );

         // Runs the application.
         Application::Run( gcnew ErrorHandler );
      }
   };

   // Creates a class to handle the exception event.
internal:
   ref class CustomExceptionHandler
   {
      // Handles the exception event. 
   public:
      void OnThreadException( Object^ /*sender*/, ThreadExceptionEventArgs^ t )
      {
         System::Windows::Forms::DialogResult result = ::DialogResult::Cancel;
         try
         {
            result = this->ShowThreadExceptionDialog( t->Exception );
         }
         catch ( Exception^ ) 
         {
            try
            {
               MessageBox::Show( "Fatal Error", "Fatal Error", MessageBoxButtons::AbortRetryIgnore, MessageBoxIcon::Stop );
            }
            finally
            {
               Application::Exit();
            }
         }

         // Exits the program when the user clicks Abort. 
         if ( result == ::DialogResult::Abort )
         {
            Application::Exit();
         }
      }

      // Creates the error message and displays it. 
   private:
      System::Windows::Forms::DialogResult ShowThreadExceptionDialog( Exception^ e )
      {
         String^ errorMsg = "An error occurred please contact the adminstrator with the following information:\n\n";
         errorMsg = String::Concat( errorMsg, e->Message, "\n\nStack Trace:\n", e->StackTrace );
         return MessageBox::Show( errorMsg, "Application Error", MessageBoxButtons::AbortRetryIgnore, MessageBoxIcon::Stop );
      }
   };

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Show:
© 2014 Microsoft