Applications Systems

Windows Service Monitor - Invalid class

When you are getting an Invalid class error in a Windows Service Monitor component in Server and Application Monitor (SAM) saying An exception occurred during polling processes, consider changing the polling method from WMI to RPC and make sure that the disable performance counters option in the registry is disabled.

First published date

10/10/2018 6:08 PM

Last published date

8/18/2025 11:10 PM

Overview

When you are getting an Invalid class error in a Windows Service Monitor component, review the polling method used to poll the node and your settings for Disable Performance Counters in the registry.

 

In the APM logs, you will find the following error message:

An exception occurred during polling processes. Error: Invalid class

Product section

Server Application Monitor

Cause

Scenario #1
There is an issue with WMI on the target machine.

Scenario #2
This problem is caused by a WMI issue on a monitored node and can be fixed by changing the polling method from WMI to RPC

Scenario #3
"Disable Performance Counters" in registry is enabled (set to '1')

    Resolution

    Scenario #1

    Verify the target machine responds to WMI queries.
    1. Perform a WBEMTEST connection: Testing WMI Connectivity with WBEMTest.
    2. Enter these queries and verify they return results with no Windows error codes:
      • SELECT * FROM Win32_Service
      • SELECT * FROM Win32_Process
      • SELECT * FROM Win32_PerfRawData_PerfProc_Process
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          3. Contact Microsoft support if you receive Windows error codes from the above queries or proceed with the other resolution scenarios.

    Scenario #2

    1. Edit the application monitor.
    2. Select all Windows Service Monitor components.
    3. Click on Multi Edit (skip this step if only 1 component exists within the application).
    4. Set Fetching Method to RPC.
    5. Save the settings.

    Scenario #3

    1. Log into the affected server
    2. Start > Run > regedit
    3. Locate "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\PerfProc\Performance"
    4. Locate "Disable Performance Counters", and confirm if its value is 0
    5. If it is 1, modify the key, and change it from 1 to 0
    6. Stop and start "Windows Management Instrument" service via services.msc
    Alternative steps that may work as a work around if the above steps do not resolve.