Unexpected Error Occured

[Bentley]

MusicBee v3.2.6827.32939 (Win10.0), 29 Oct 2018 14:42:

System.NullReferenceException: Object reference not set to an instance of an object.
   at MusicBeePlugin.BackupType.save(String fileName)
   at MusicBeePlugin.BackupIndex.saveBackup(String backupName, String statusbarText, Boolean isAutocreatedParam)
   at MusicBeePlugin.Plugin.regularAutobackup(Object state)
   at System.Threading.TimerQueueTimer.CallCallbackInContext(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.TimerQueueTimer.CallCallback()
   at System.Threading.TimerQueueTimer.Fire()
   at System.Threading.TimerQueue.FireNextTimers()
   at System.Threading.TimerQueue.AppDomainTimerCallback()

Was told it could be an plugin so turned them off seemed to work fine then tried one at time and 'Adds some tagging tools to MusicBee' looks like the one causing the problem. It errors after 10-20 minutes of play. I have not added anything to MusicBee and last update was a few months ago so why this error started in the last week or so seems strange.