Error ItemRegistry

Hi,
One of the PowerPlug’s was defect and i replaced the plug. but now i get a strange message:

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[ERROR] [le.handler.ItemStateConditionHandler] - Item with name KeukenBoilerN015_Electricmeterwatts not found in ItemRegistry.

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but i deleted the node 15 in my setup. Where and how can i change the ItemRegistry?

This means that something in openHAB (maybe a rule, or something in the UI?) is trying to access an Item called KeukenBoilerN015_Electricmeterwatts, but this Item doesn’t exist.