Some WMI instances can have their first method call fail and get-member not work in PowerShell V1
Due to a problem retrieving the available methods in V1 that we have worked around for the upcoming version of PowerShell, you might experience that the first method call to a WMI object fails with a message that mentions:
Exception calling GetType() with “0” argument(s): “You cannot call a method on a null-valued expression.”
This happens when calling the first method in objects that are not in the root\cimv2 like:
$instance=([wmiclass]"root\MyNamespace:MyObject").CreateInstance()
$instance.GetType()
As a PowerShell V1 workaround, a first call to GetType() can be performed to prevent the failure in other method calls.
Also, the get-member cmdlet will fail to work with the instance above with the following error message:
Get-Member : Exception retrieving members: “Not Found “
As a PowerShell V1 workaround, you can list the properties available in the object by calling:
$instance.PsObject.Properties | format-table Name
We apologize for the inconvenience this might cause.
Lucio Silveira [MSFT]
Software Developer Engineer
Visit the Windows PowerShell Team blog at: http://blogs.msdn.com/PowerShell
Visit the Windows PowerShell ScriptCenter at: http://www.microsoft.com/technet/scriptcenter/hubs/msh.mspx
