Task applicationcontent has failed with an unknown exception

XML Error -

Task applicationcontent has failed with an unknown exception

SharePoint 2013 Product Configuration wizard Failed during the Cumulative Update installation with below error

Task applicationcontent has failed with an unknown exception

 ERR                  Exception: System.NullReferenceException: Object reference not set to an instance of an object.

   at Microsoft.SharePoint.Administration.SPAspConfigurationFile.ApplyActionToXmlDocument(XmlDocument xdAction, XmlDocument xd, String sourceFileName, SupportedXmlDocutmentActions supportedActions)

   at Microsoft.SharePoint.Administration.SPAspConfigurationFile.MergeWebConfig(XmlDocument xdWebConfig, String fileMask)

   at Microsoft.SharePoint.Administration.SPWebService.ApplyApplicationContentToLocalServer()

   at Microsoft.SharePoint.PostSetupConfiguration.ApplicationContentTask.Run()

   at Microsoft.SharePoint.PostSetupConfiguration.TaskThread.ExecuteTask()

Finally Microsoft Article came in to rescue saying this error caused because Web Application Web Configs are having Commented lines <!—comments --!>

When we remove the comments in Web Config  PSConfig executed successfully 

Microsoft Article

https://docs.microsoft.com/en-us/sharepoint/support/server-admin/nullreferenceexception-for-configuration-wizard