A [Room] Tag was deleted, but the corresponding [Room] still exists. You can place another tag for the [Room] using the [Room] Tag tool or select the [Room] and delete it. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
Syntax
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