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Exchange 2016 – Event Error 4127

One of the event errors that may appear in the exchange server’s event viewer is event error 4127 as following:

Process powershell.exe (PID=16988). Component: Microsoft.Exchange.Data.Directory.ConfigurationSettingsADNotificationException: Error running AD operation. —> Microsoft.Exchange.Data.Directory.ADTopologyUnexpectedException: Unexpected error when calling the Microsoft Exchange Active Directory Topology service on server ‘TopologyClientTcpEndpoint (localhost)’. Error details: Access is denied.. —> System.ServiceModel.Security.SecurityAccessDeniedException: Access is denied.

It should be a permission related to Exchange PowerShell and you can check the following three solution:

  • Recycle the PowerShell App Pool in IIS manager: MSExchangePowerShellAppPool and MSExchangePowerShellFrontEndAppPool:

  • Reset the PowerShell virtual directory in EAC:

    Open Exchange Admin Center > Servers > Virtual directories:

  • If the issue still exist you should delte and recreate the powershell virtual directory as following
    • Get the PowerShell virtual directory Identity

    Get-PowerShellVirtualDirectory | Fl Server,Identity

    • Delete the PowerShell virtual directory

    Remove-PowerShellVirtualDirectory “virtual directory Identity”

    • Create the PowerShell virtual directory

      New-PowerShellVirtualDirectory -Name Powershell -RequireSSL:$False

    • Run iisreset in cmd prompt to refresh

Ratish Nair

Microsoft MVP | Office Servers and Services

Team @MSExchangeGuru

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