A .NET Framework 2.0-based application that targets to the x64 platform crashes for an uncaught ThreadAbortException exception


Consider the following scenario for a Microsofot .NET Framework 2.0-based application:
  • The application targets to x64 platform or Any CPU.
  • When you build the corresponding project, you specify the /o+ flag in the csc.exe command line. Or, you select the Optimize Code flag in the Build section of the Project Properties page in Visual Studio.
  • The source file in the project contains a try/catch block inside a loop. There is no execution code between the end of the catch block and the end of the loop. A ThreadAbortException exception is raised after the catch block.
  • The source file contains catch blocks in a higher function level that aims to catch the ThreadAbortException exception.
  • You run the application.
In this scenario, the exception is not caught and the application crashes unexpectedly.


Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.


There are no prerequisites to install this hotfix.

Restart requirement

You must restart the computer after you apply the hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.
For all supported x86-based versions of Windows 7
File nameFile versionFile sizeDateTime
For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
File nameFile versionFile sizeDateTime
For all supported IA-64-based versions of Windows Server 2008 R2
File nameFile versionFile sizeDateTime
To work around this issue, add code between the end of the catch block and the end of the loop.
To reproduce this issue, compile the following example code by using the csc.exe /o+ command and generate an application that targets to the x64 platform by using the .NET Framework 2.0.
using System;
using System.Threading;

class P
private static void Foo()
while (true)
catch (Exception)
// throw;
Console.WriteLine("Inside catch");

public static void Main(string[] a)
catch (System.Threading.ThreadAbortException)

Before you install the hotfix, the application crashes; after you install the hotfix, you receive the following output in Console:


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates