User-mode Programs Cannot Allocate Blocks of Virtual Memory

Article translations Article translations
Article ID: 216540 - View products that this article applies to.
This article was previously published under Q216540
This article has been archived. It is offered "as is" and will no longer be updated.
Expand all | Collapse all


User-mode programs are unable to allocate blocks of virtual memory (calls to VirtualAlloc() do not succeed). This may result in the inability to create threads, mutexes, critical sections, and so on.


This problem occurs when a VirtualAlloc() critical section object is being called to initialize part of the structure (DebugInfo). VirtualAlloc() reserves virtual memory on a 64 KB boundary. However, this structure only allocates 4 KB (reserve and commit) blocks of virtual memory, thereby leaving 60 KB unused. Over time, this results in fragmentation of virtual memory and may reduce the size of contiguous blocks available to user-mode programs.


To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:
For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:


Microsoft has confirmed that this is a problem in Windows NT 4.0. This problem was first corrected in Windows NT 4.0 Service Pack 5.


Article ID: 216540 - Last Review: November 2, 2013 - Revision: 3.0
Applies to
  • Microsoft Windows NT Server 4.0 Standard Edition
kbnosurvey kbarchive kbhotfixserver kbqfe kbbug kbfix KB216540

Contact us for more help

Contact us for more help
Connect with Answer Desk for expert help.
Get more support from