You are currently offline, waiting for your internet to reconnect

Some applications cannot access the serial port in Windows Server 2003

Support for Windows Server 2003 ended on July 14, 2015

Microsoft ended support for Windows Server 2003 on July 14, 2015. This change has affected your software updates and security options. Learn what this means for you and how to stay protected.

This article has been archived. It is offered "as is" and will no longer be updated.
Some applications may not be able to communicate through the COM serial port on your Microsoft Windows Server 2003-based computer. You may experience this problem with custom applications that use the "return quickly" feature of the Windows COM port driver. For example, this problem may occur with custom applications that use the serial port control (MsComm32.ocx) that is included with Microsoft Visual Basic 6.0.
This problem occurs because the redirected port implementation sets the status to pending, and this affects serial COM software that relies on the "return quickly" feature.

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.

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 Web site: 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.


No prerequisites are required.

Restart requirement

You do not have to restart your computer after you apply this 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) 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 tool in Control Panel.
Windows Server 2003 64-Bit Edition
   Date         Time   Version            Size    File name   --------------------------------------------------------------   19-Apr-2004  14:53  5.2.3790.163      597,504  Rdpdr.sys   12-Apr-2004  19:56                        271  Branches.inf   19-Apr-2004  16:48                      9,766   19-Apr-2004  16:41                        354  Updatebr.inf   19-Apr-2004  16:42                      6,249  Update_rtmqfe.inf
Windows Server 2003 32-bit editions
   Date         Time   Version            Size    File name   --------------------------------------------------------------   19-Apr-2004  17:42  5.2.3790.163      188,416  Rdpdr.sys   12-Apr-2004  22:56                        271  Branches.inf   19-Apr-2004  19:48                      9,766   19-Apr-2004  19:37                        354  Updatebr.inf   19-Apr-2004  19:37                      5,987  Update_rtmqfe.inf
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For additional information about standard terminology used to describe software updates, 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

Article ID: 838291 - Last Review: 12/08/2015 06:36:05 - Revision: 1.11

  • Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
  • Microsoft Windows Server 2003, Standard Edition (32-bit x86)
  • Microsoft Windows Server 2003, Enterprise x64 Edition
  • kbnosurvey kbarchive kbautohotfix kbqfe kbhotfixserver kbserial kbconnpts kbcomservices kbwinserv2003presp1fix kbhardware kbinterop kbfix kbbug KB838291