Exception.InnerException Property


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Gets the Exception instance that caused the current exception.

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

public Exception InnerException { get; }

Property Value

Type: System.Exception

An object that describes the error that caused the current exception. The InnerException property returns the same value as was passed into the Exception(String, Exception) constructor, or null if the inner exception value was not supplied to the constructor. This property is read-only.

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 the cause of 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.

using System;

public class AppException : Exception
   public AppException(String message) : base (message)

   public AppException(String message, Exception inner) : base(message,inner) {}

public class Example
   public static void Main()
      Example ex = new Example();

      try {
      catch(AppException e) {
         Console.WriteLine ("In catch block of Main method.");
         Console.WriteLine("Caught: {0}", e.Message);
         if (e.InnerException != null)
            Console.WriteLine("Inner exception: {0}", e.InnerException);

   public void ThrowInner ()
      throw new AppException("Exception in ThrowInner method.");

   public void CatchInner() 
      try {
      catch (AppException e) {
         throw new AppException("Error in CatchInner caused by calling the ThrowInner method.", e);
// The example displays the following output:
//    In catch block of Main method.
//    Caught: Error in CatchInner caused by calling the ThrowInner method.
//    Inner exception: AppException: Exception in ThrowInner method.
//       at Example.CatchInner()

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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