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Home > Success Center > Network Performance Monitor (NPM) > Core Business Layer plugin does not start

Core Business Layer plugin does not start

Updated June 23, 2017


The Core Business Layer plugin does not start and the following error is found in the Core.BusinessLayer.log file:

2017-03-28 09:51:08,918 [7] FATAL SolarWinds.Orion.Core.BusinessLayer.CoreBusinessLayerPlugin - (null)  Unhandled Exception caught in plugin startup.
System.ArgumentException: An item with the same key has already been added.
   at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at SolarWinds.Orion.Core.BusinessLayer.BackgroundInventory.InventoryManager..ctor(Int32 engineID)
   at SolarWinds.Orion.Core.BusinessLayer.CoreBusinessLayerPlugin.ScheduleBackgroundInventory()
   at SolarWinds.Orion.Core.BusinessLayer.CoreBusinessLayerPlugin.Start()


All Orion Platform versions


This issue occurs when there is a duplicate or an older DLL present in the installation folder.


Remove the duplicate DLLS.

Note: It is also possible that there are duplicate DLLs in a duplicate installation folder and in the backup and hotfix folders.


Last modified
21:46, 22 Jun 2017