FIX: An access violation occurs when you run a Visual C++ 2010-based application for x64-based platforms if you use the "/O2" compiler option to build the project

Applies to: Visual Studio 2010


Consider the following scenario:
  • You have a Visual C++ 2010 project. The source code of the project has a structure or class that exceeds 64 bytes.
  • You build the project for an x64-based platform, and you use the /O2 compiler option. 
  • You run the application.
  In this scenario, an access violation occurs, and the application crashes.


This issue occurs because the x64-based compiler of Visual Studio 2010 optimizes the code by adjusting the allocation alignment of data from 64 bytes to 16 bytes. Therefore, a memory issue occurs for the objects that exceed 64 bytes.


Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might 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 download this hotfix from the MSDN Code Gallery, visit the following Microsoft website:

Note The MSDN Code Gallery displays the languages for which the hotfix is available. If you do not see your language listed, it is because the Code Gallery resource page is not available for that language.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website:
You can also download this hotfix by visiting the following Microsoft website:


To apply this hotfix, you must have Visual Studio 2010 installed.

Restart requirement

You do not have to 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.
File nameFile versionFile sizeDateTimePlatform


To work around this issue, do not use the /O2 compiler option when you build the project.


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