An application that calls the CloseHandle function on a serial port cannot be exited in Windows Vista, Windows 7, Windows Server 2008, or Windows Server 2008 R2

Applies to: Windows 7 EnterpriseWindows 7 Home BasicWindows 7 Home Premium


Assume that you have an application that uses the serial ports in Windows Vista, Windows 7, Windows Server 2008, or Windows Server 2008 R2. In this scenario, when the application calls the CloseHandle function on a serial port, the function does not return, and the application cannot be exited. To temporarily resolve this issue, you have to restart the computer.


This problem may occur because the Serial.sys file is stuck in an infinite loop after the CloseHandle function is called.


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 the problem described in this article. 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.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

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: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


You must have one of the following installed to apply this hotfix:
  • Windows 7 Service Pack 1
  • Windows Server 2008 R2 Service Pack 1
  • Windows Vista Service Pack 2
  • Windows Server 2008 Service Pack 2
See Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R for more information.

See How to obtain the latest Windows Vista service pack for more information.

See How to obtain the latest service pack for Windows Server 2008 for more information.

Restart information

You must restart the computer after you apply this hotfix.

Replacement information

This hotfix does not replace any previously released hotfix.


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