The MOUNTMGR.SYS File is an Incorrect Version

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2006-02-13

The Microsoft® Exchange Server Analyzer Tool reads the following registry key to determine whether Microsoft Windows® Server 2003 is installed: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\

The Exchange Server Analyzer also performs the following queries:

  • The Win32_OperatingSystem Microsoft Windows Management Instrumentation (WMI) class to determine whether Windows Server 2003 Service Pack 1 is installed.

  • The Win32_Service WMI class to determine whether Cluster service is running.

  • The Win32_Volume WMI class to determine whether there are Volume Mount Points present.

  • The CIM_Datafile WMI class to determine whether the value of the Version key for Mountmgr.sys is less then 2443.

The Exchange Server Analyzer displays an error if the following conditions are true:

  • The Version key for Mountmgr.sys is less then 2443.

  • The server is a node of a Cluster running Windows Server 2003 Service Pack 1.

  • The server has volume mount points.

The version of Mountmgr.sys installed on the cluster node may cause volume mount point failures. This problem occurs because of a problem in the Mountmgr.sys driver. This is an intermittent timing problem that can occur when a volume arrives to be mounted to a mount point.


Generally, this problem does not occur in a non-clustered environment. In a non-clustered environment, the timing of the volume mount process is different.

For more information about this issue, see Microsoft Knowledge Base article 898790, "Volume mount points on disks in a server cluster may intermittently become unavailable after you install Windows Server 2003 Service Pack 1" (