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Exception.InnerException Property

Gets the Exception instance that caused the current exception.

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

'Declaration
Public ReadOnly Property InnerException As Exception

Property Value

Type: System.Exception
An instance of Exception that describes the error that caused the current exception. The InnerException property returns the same value as was passed into the constructor, or a null reference (Nothing in Visual Basic) if the inner exception value was not supplied to the constructor. This property is read-only.

Implements

_Exception.InnerException

When an exception X is thrown as a direct result of a previous exception Y, the InnerException property of X should contain a reference to Y.

Use the InnerException property to obtain the set of exceptions that led to the current exception.

You can create a new exception that catches an earlier exception. The code that handles the second exception can make use of the additional information from the earlier exception to handle the error more appropriately.

Suppose that there is a function that reads a file and formats the data from that file. In this example, as the code tries to read the file, an IOException is thrown. The function catches the IOException and throws a FileNotFoundException. The IOException could be saved in the InnerException property of the FileNotFoundException, enabling the code that catches the FileNotFoundException to examine what causes the initial error.

The InnerException property, which holds a reference to the inner exception, is set upon initialization of the exception object.

The following example demonstrates throwing and catching an exception that references an inner exception.

Imports System

Public Class MyAppException
   Inherits ApplicationException

   Public Sub New(message As [String])
      MyBase.New(message)
   End Sub 'New 

   Public Sub New(message As [String], inner As Exception)
      MyBase.New(message, inner)
   End Sub 'New 
End Class 'MyAppException

Public Class ExceptExample

   Public Sub ThrowInner()
      Throw New MyAppException("ExceptExample inner exception")
   End Sub 'ThrowInner

   Public Sub CatchInner()
      Try 
         Me.ThrowInner()
      Catch e As Exception
         Throw New MyAppException("Error caused by trying ThrowInner.", e)
      End Try 
   End Sub 'CatchInner
End Class 'ExceptExample

Public Class Test

   Public Shared Sub Main()
      Dim testInstance As New ExceptExample()
      Try
         testInstance.CatchInner()
      Catch e As Exception
         Console.WriteLine("In Main catch block. Caught: {0}", e.Message)
         Console.WriteLine("Inner Exception is {0}", e.InnerException)
      End Try 
   End Sub 'Main
End Class 'Test

This code has the following output:

In Main
  catch block. Caught: Error caused by trying ThrowInner. Inner Exception is
  MyAppException: ExceptExample inner exception at ExceptExample.ThrowInner() at
  ExceptExample.CatchInner()

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, 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.

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