"The network BIOS command limit has been reached" error message in Windows Server 2003, in Windows XP, and in Windows 2000 Server

After you install Microsoft Windows Server 2003, Microsoft Windows XP, or Microsoft Windows 2000 Server, you may receive the following error message:

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
  .

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:

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 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.

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.

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: For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base: 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.