A 32-bit application cannot use the NetBIOS API to receive data on a computer that is running a 64-bit version of Windows Vista

This article has been archived. It is offered "as is" and will no longer be updated.
You are running a 32-bit application on a computer that is running a 64-bit version of Windows Vista. The application uses the NetBIOS API to communicate over the network. In this Windows on Windows 64 (WOW64) environment, the 32-bit application can open a connection, and it can send data. However, the application cannot use the NetBIOS API to receive data.

For example, the 32-bit application successfully makes an NCBSEND command call. However, the NCBRECVANY command cannot receive data correctly.

Note This problem does not occur in the following scenarios:
  • You run the 32-bit application in a 32-bit version of Windows Vista.
  • You compile code for the 32-bit application into a 64-bit application. Then, you run the 64-bit application in the 64-bit version of Windows Vista.
This problem occurs because of an error in the NetBIOS interface driver (NetBIOS.sys). When the NetBIOS interface driver is receiving data, the driver sometimes does not convert the network connection block (NCB) structure from the 64-bit version to the 32-bit version. Therefore, the 32-bit application cannot understand the NCB structure.

Service pack information

To resolve this problem, obtain the latest service pack for Windows Vista. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
935791 How to obtain the latest Windows Vista service pack

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 have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other previously released hotfixes.

Registry information

To use one of the hotfixes in this package, you do not have to make any changes to the registry.

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.
Windows Vista, 64-bit versions
File nameFile versionFile sizeDateTimePlatform
Amd64_80c93bbf8c8995c186c3c6d21846afbf_31bf3856ad364e35_6.0.6000.20586_none_2dc90416d0a47dd4.manifestNot applicable71326-Apr-200715:58Not applicable
Amd64_afc0ea3989214a77de4de8072cfc378b_31bf3856ad364e35_6.0.6000.20586_none_20cc73e1c3b56f6c.manifestNot applicable71126-Apr-200715:58Not applicable
Amd64_microsoft-windows-authentication-authui_31bf3856ad364e35_6.0.6000.20586_none_6664f54fc9f7df4a.manifestNot applicable59,41626-Apr-200716:04Not applicable
Package_1_for_kb936460~31bf3856ad364e35~amd64~~ applicable1,80026-Apr-200715:58Not applicable
Package_2_for_kb936460~31bf3856ad364e35~amd64~~ applicable2,01926-Apr-200715:58Not applicable
Update.mumNot applicable1,90926-Apr-200715:58Not applicable
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Vista Service Pack 1.
Windows on Windows 64 (WOW64) is a compatibility environment that enables 32-bit Windows-based applications to run on 64-bit Windows-based operating systems.

For more information about the same problem in Windows Server 2003, click the following article number to view the article in the Microsoft Knowledge Base:
940074 A 32-bit application cannot use the NetBIOS API to receive data on a computer that is running a 64-bit version of Windows Server 2003
For more information about software update terminology, 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
NetBIOS 32-bit 64-bit receive WoW64 NCBRECV NCBSEND VISTA x64

Article ID: 940480 - Last Review: 01/16/2015 10:00:25 - Revision: 4.0

Windows Vista Enterprise 64-bit Edition, Windows Vista Home Premium 64-bit Edition, Windows Vista Ultimate 64-bit Edition, Windows Vista Business 64-bit Edition

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