Article ID: 810886
Article Last Modified on 3/19/2007
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
- Microsoft Windows 2000 Service Pack 3
- Microsoft Windows 2000 Service Pack 3
Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows registry
SYMPTOMS
After you install Microsoft Windows Server 2003, Microsoft Windows XP, or Microsoft Windows 2000 Server, you may receive the following error message:
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
MaxCmdsregistry value setting on the client is less than 50, or theMaxMpxCtregistry 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
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
To resolve this issue, verify that the MaxCmds and MaxMpxCt registry values are set to 50 or more. To do this, follow these steps:
- Click Start, click Run, type regedit, and then click OK.
- Locate and then click the following key in the registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanworkstation\parameters
- In the right pane, double-click the MaxCmds value.
- 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 theMaxCmdsregistry value to 500 or more. For more information, click the following article number to view the article in the Microsoft Knowledge Base:232476 Terminal Server client connections and logon limited by MaxWorkItem and MaxMpxCt values
- Locate and then click the following key in the registry:
Note Make sure that you make this change to the
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters
lanmanserver\parametersregistry key and not to thelanmanworkstation\parametersregistry key mentioned in step 2. - In the right-pane, double-click the MaxMpxCt value.
Note On SMB servers that are running a version of Windows earlier than Windows 2000, theMaxMpxCtregistry entry is namedMaxMpxCount, but has the same function. - In the Value data box, verify that the value is 50 or more.
Note TheMaxMpxCtvalue determines the maximum number of simultaneous, active requests that the server permits from an individual client. - Quit Registry Editor.
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 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 Terminal Server client connections and logon limited by MaxWorkItem and MaxMpxCt values
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:
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.
Additional query words: AS/400 AS400 max_mux MaxMux MaxMPX MaxWorkItems AFS error 56 "0xc00000c1"
Keywords: kberrmsg kbtshoot kbprb KB810886
