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Article ID: 810886 - Last Review: May 24, 2010 - Revision: 8.0

SYMPTOMS

After you install Microsoft Windows Server 2003, Microsoft Windows XP, or Microsoft Windows 2000 Server, you may receive the following error message:
The network BIOS command limit has been reached.

CAUSE

This issue may occur if the following conditions are true:
  • This issue may occur if the client computer submits simultaneous, long-term requests against a file server that uses the Server Message Block (SMB) protocol. An example of a long-term request is when a client computer uses the FindFirstChangeNotification function to monitor a server share for changes.
  • This issue may occur if the MaxCmds registry value setting on the client is less than 50, or the MaxMpxCt registry value setting on the server is less than 50.

    Note The MaxMpxCt registry value setting may have a different name on other SMB/CIFS implementations. The Common Internet File System (CIFS) specification refers to it as MaxMpxCount.

RESOLUTION

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756  (http://support.microsoft.com/kb/322756/ ) How to back up and restore the registry in Windows


To resolve this issue, verify that the MaxCmds and MaxMpxCt registry values are set to 50 or more. To do this, follow these steps:
  1. Click Start, click Run, type regedit, and then click OK.
  2. Locate and then click the following key in the registry:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanworkstation\parameters
  3. In the right pane, double-click the MaxCmds value.
  4. In the Value data box, verify that the value is 50 or more.

    Note In a Microsoft Windows Terminal Services environment, you may have to set the MaxCmds registry value to 500 or more. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
    232476  (http://support.microsoft.com/kb/232476/ ) Terminal Server client connections and logon limited by MaxWorkItem and MaxMpxCt values
  5. Locate and then click the following key in the registry:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters
    Note Make sure that you make this change to the lanmanserver\parameters registry key and not to the lanmanworkstation\parameters registry key mentioned in step 2.
  6. In the right-pane, double-click the MaxMpxCt value.

    Note On SMB servers that are running a version of Windows earlier than Windows 2000, the MaxMpxCt registry entry is named MaxMpxCount, but has the same function.
  7. In the Value data box, verify that the value is 50 or more.

    Note The MaxMpxCt value determines the maximum number of simultaneous, active requests that the server permits from an individual client.
  8. Quit Registry Editor.
  9. Restart the server.
Note The MaxCmds and MaxMpxCt registry entries are REG_DWORD decimal entries. If they do not exist on your computer, you can create them as new REG_DWORD values. The range of values for these registry entries is between 0 and 65535.

MORE INFORMATION

The maximum number of simultaneous, active requests between an SMB client and the server is determined when a client/server session is negotiated. The maximum number of requests that a client supports is determined by the MaxCmds registry value. The maximum number of requests that a server supports is determined by the MaxMpxCt registry value. For a particular client and server pair, the number of simultaneous, active requests is the lesser of these two values.

In a BizTalk environment, add both registry values to the BizTalk server and the remote UNC Share server.

To track the number of simultaneous, active requests on an SMB client, add the Current Commands counter in the SMB Redirector performance object to Performance Monitor.

REFERENCES

For more information about the MaxMpxCt and MaxCmds values in Windows 2000, click the following article number to view the article in the Microsoft Knowledge Base:
271148  (http://support.microsoft.com/kb/271148/ ) MaxMpxCt and MaxCmds limits in Windows 2000
For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
232476  (http://support.microsoft.com/kb/232476/ ) Terminal Server client connections and logon limited by MaxWorkItem and MaxMpxCt values
811005  (http://support.microsoft.com/kb/811005/ ) User authentication to services such as Microsoft Exchange Server may time out on a member server
To obtain a compiled HTML help file of the CIFS/SMB specification, visit the following Microsoft Web site:
http://www.microsoft.com/downloads/details.aspx?FamilyID=c4adb584-7ff0-4acf-bd91-5f7708adb23c&displaylang=en (http://www.microsoft.com/downloads/details.aspx?FamilyID=c4adb584-7ff0-4acf-bd91-5f7708adb23c&displaylang=en)
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

APPLIES TO
  • Microsoft Windows Server 2003, Standard Edition (32-bit x86)
  • Microsoft Windows Server 2003, Web Edition
  • Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
  • Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
  • Microsoft Windows XP Home Edition
  • Microsoft Windows XP Professional
  • Microsoft Windows 2000 Service Pack 3
  • Microsoft Windows 2000 Advanced Server SP3
  • Microsoft Windows Server 2003, Enterprise x64 Edition
  • Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
  • Microsoft Windows Server 2003, Standard x64 Edition
  • Microsoft Windows Server 2003, Datacenter x64 Edition
  • Microsoft Windows Server 2003, Datacenter Edition for Itanium-Based Systems
Keywords: 
kbtshoot kberrmsg kbprb KB810886
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