WMI Flakiness / Enumerating User Accounts

Question

I am using WMI to enumerate users of the computer but with some customers I am getting cryptic exceptions and/or the code doesn't work as expected. For one customer NO user account information is returned from this simple code:

  SelectQuery query = new SelectQuery("Win32_UserAccount", string.Format("Domain='{0}'", Environment.MachineName));
  ManagementObjectSearcher searcher = new ManagementObjectSearcher(query);
  foreach (ManagementObject mObject in searcher.Get()) {
    Console.WriteLine((string)mObject["Name"]);
  }

But for the same customer, I am able to enumerate groups using this code which produces output like "Administradores", "Convidados", "Distributed COM - Usuários", etc.

  SelectQuery query = new SelectQuery("Win32_Group", string.Format("Domain='{0}'", Environment.MachineName));
  ManagementObjectSearcher searcher = new ManagementObjectSearcher(query);
  foreach (ManagementObject mObject in searcher.Get()) {
    Console.WriteLine((string)mObject["Name"]);
  }

Attempting to enumerate users in a particular group using the code below generates an exception. I am passing in Environment.MachineName as the domain name and a valid group name.

public static void GetUsersInGroup(string domainName, string groupName) {
  string findUsersQueryText = string.Format("GroupComponent=\"Win32_Group.Domain='{0}',Name='{1}'\"", domainName, groupName);
  SelectQuery query = new SelectQuery("Win32_GroupUser", findUsersQueryText);
  using (ManagementObjectSearcher searcher = new ManagementObjectSearcher(query)) {
    foreach (ManagementObject foundObject in searcher.Get()) {
      foreach (var property in foundObject.Properties) {
        if (property.Name == "PartComponent") {
          ManagementPath managementPath = new ManagementPath(foundObject["PartComponent"].ToString());
          if (managementPath.ClassName == "Win32_UserAccount") {
            using (ManagementObject userAccount = new ManagementObject(managementPath)) {
              foreach (var x in userAccount.Properties) {
                //Exception raised here while trying to enumerate properties
                //System.Management.ManagementException: Not found 
                //  em System.Management.ManagementException.ThrowWithExtendedInfo(ManagementStatus errorCode)
                //  em System.Management.ManagementObject.Initialize(Boolean getObject)
                //  em System.Management.ManagementBaseObject.get_Properties()
                //  em WmiTest.AccountManager.GetUsersInGroup(String domainName, String groupName)
                Console.WriteLine(String.Format("  Name: '{0}' Value: '{1}'\r\n", x.Name ?? "null", x.Value ?? "null"));
              }
            }
          }
        }
      }
    }
  }
}

We've tried deleting the WMI repository but the problem remains.

What could be causing these problems with the WMI code? How can I get more information about what is going wrong?

Answer 1

Nearly ALL WMI problems I've run into when it works on one client but not another boil down to the OS and service pack level.

MS has made a LOT of fixes/changes/additions to the WMI objects over the years. We have one client with 17,000 machines that we installed a service that monitors some WMI information on. The machines run the gamut from XP RTM on up to Windows 7.

That was a nightmare. The differences in the level of WMI information available was astounding. For example, just getting the CPU type was hit or miss depending on patch level.

I would say that Step 1 is to get the client machine patched up to the latest service pack available for that OS. Then try again.