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My Powershell sensor returns an error message. What can I do?



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When I add a Windows Updates Status (Powershell) sensor to my PRTG installation, an error message appears.

The error message tells me that “An unknown security error occurred”. The connection to the remote server failed and WinRM is unable to process the request. There seems to be an issue with Kerberos authentication.


The error message tells me that there are "No Logon Servers Available".


The error message tells me about "Unauthorized Access".

I get this error message also after creating other PowerShell sensors. What can I do?

authentication error error-messages kerberos powershell prtg security windows-updates-status winrm

Created on Nov 8, 2013 3:54:41 PM by  Gerald Schoch [Paessler Support]

Last change on Mar 20, 2014 12:45:59 PM by  Gerald Schoch [Paessler Support]

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This article applies to PRTG Network Monitor 13 or later

Tips for Running Sensors Using PowerShell Scripts

There are a few things to consider when using PowerShell sensors. This applies to pre-configured sensors, for example, the Windows Updates Status sensor, as well as to custom sensors which execute a PowerShell script, for example, the EXE/Script Advanced sensor. Please see below for possible resolution steps for PowerShell errors.

"Unknown Security Error" with PowerShell Sensors

If you added a PowerShell sensor to your PRTG installation, you may sometimes encounter an error message as given below (or similar). However, your computers are in the domain and credentials are valid.

In this case, please use the FQDN (Fully Qualified Domain Name) instead of the IP address. You can specify the FQDN in the IPv4 Address/DNS Name field in the settings of the sensor’s parent device.

Error Message

Connecting to remote server failed with the following error message: WinRM cannot process the request. The following error occurred while using Kerberos authentication: Unknown security error. Possible causes are: -The user name or password specified are invalid. -Kerberos is used when no authentication method and no user name are specified. -Kerberos accepts domain user names, but not local user names. -The Service Principal Name (SPN) for the remote computer name and port does not exist. -The client and remote computers are in different domains and there is no trust between the two domains. After checking for the above issues, try the following: -Check the Event Viewer for events related to authentication. -Change the authentication method; add the destination computer to the WinRM TrustedHosts configuration setting or use HTTPS transport. Note that computers in the TrustedHosts list might not be authenticated. -For more information about WinRM configuration, run the following command: winrm help config. For more information, see the about_Remote_Troubleshooting Help topic.

"No Logon Servers Available" with PowerShell Sensors

Please see this article if WinRM cannot process the request and you encounter a No Logon Servers Available error:

"Unauthorized Access" with PowerShell Sensors

64bit Windows systems run two PowerShell versions, the 64bit and the 32bit PowerShell. Because PRTG calls the 32bit PowerShell, please ensure that you have set the correct execution policy for the 32bit version and not only for 64bit. The execution policy should be unrestricted: Set-ExecutionPolicy Unrestricted Otherwise your PowerShell sensors will throw the error message Unauthorized Access.

See also: Powershell 32bit or 64bit and Execution Policy

Also note that the user context may be different when the script is executed by the PRTG probe (by default this is the "LOCAL SYSTEM" account) and not by your Windows account when running the script manually.

Created on Nov 8, 2013 3:59:09 PM by  Gerald Schoch [Paessler Support]

Last change on Mar 17, 2015 10:52:45 AM by  Gerald Schoch [Paessler Support]

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Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.