at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
at System.Web.UI.ObjectStateFormatter.Deserialize(Stream inputStream)
What is it exactly?