Maximum NT User Handles Per Process Is 10,000 in Windows XP (327699)


The information in this article applies to:

  • Microsoft Windows XP Home Edition
  • Microsoft Windows XP Professional
This article was previously published under Q327699
IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

Programs that require many NT User handles may stop working when they reach approximately 10,000 handles. For example, this might occur when a program tries to use many NetDDE links.

CAUSE

There is a hard-coded limit of 10,000 NT User handles. This is designed to prevent "bad" (incorrectly behaving) programs from allocating too many NT User handles.

RESOLUTION

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it 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 Windows XP service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

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 typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix 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. 
      Date      Time   Version      Size       File name
   ------------------------------------------------------
   13-Aug-2002  12:04  5.1.2600.54  1,671,040  Win32k.sys

Required Registry Values

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To use this hotfix, you must create or modify the following registry values to specify the number of NT User handles that you want to allow. The maximum number is 18,000.

HKLM\Software\Microsoft\Windows NT\CurrentVersion\Windows\USERProcessHandleQuota

HKLM\Software\Microsoft\Windows NT\CurrentVersion\Windows\USERPostMessageLimit (REG_DWORD)

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.
Modification Type:MinorLast Reviewed:10/11/2005
Keywords:kbHotfixServer kbQFE kbbug kbfix kbQFE KB327699
©2004 Microsoft Corporation. All rights reserved.