We recently receiving this error on log in, starting Crawler, Background services etc.  We are only receiving this error in our prod instances test instances seems to be fine. Not sure where to start troubleshooting this issue. Any advice is appreciated. Thanks in advance. 

System.TypeInitializationException: The type initializer for 'Trisoft.InfoShare.BackgroundTask.Configuration.ProjectConfiguration' threw an exception. ---> System.MissingMethodException: Method not found: 'System.Xml.XmlReaderSettings Trisoft.Utilities.Common.Helpers.IshXmlHelper.CreateXmlReaderSettings(Boolean)'.
   at Trisoft.InfoShare.Configuration.ExceptionResource.PopulateMessages()
   at Trisoft.InfoShare.Configuration.ExceptionResource..ctor(String filePath)
   at Trisoft.InfoShare.Configuration.ExceptionResources..ctor(String resourceDirectory)
   at Trisoft.InfoShare.Configuration.ProjectConfiguration..ctor()
   at Trisoft.InfoShare.Configuration.ProjectConfiguration.get_Current()
   at Trisoft.InfoShare.BackgroundTask.Configuration.ProjectConfiguration.get_ApplicationName()
   at Trisoft.InfoShare.BackgroundTask.Identity.BackgroundTaskAuthorization.Initialize()
   at Trisoft.InfoShare.BackgroundTask.Configuration.ProjectConfiguration..cctor()
   --- End of inner exception stack trace ---
   at Trisoft.InfoShare.BackgroundTask.Configuration.ProjectConfiguration.get_ApplicationName()
   at BackgroundTask.BackgroundTask.Process(String[] args)
   at BackgroundTask.BackgroundTask.OnStart(String[] args)
   at System.ServiceProcess.ServiceBase.ServiceQueuedMainCallback(Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.ServiceProcess.ServiceBase.Run(ServiceBase[] services)
   at BackgroundTask.Program.Main(String[] args)
Program.Main