Type 'Telerik.Web.UI.RadListBoxItemCollection' in Assembly 'Telerik.Web.UI, Version=2013.2.717.40, Culture=neutral, PublicKeyToken=121fae78165ba3d4' is not marked as serializable. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Runtime.Serialization.SerializationException: Type 'Telerik.Web.UI.RadListBoxItemCollection' in Assembly 'Telerik.Web.UI, Version=2013.2.717.40, Culture=neutral, PublicKeyToken=121fae78165ba3d4' is not marked as serializable.Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SerializationException: Type 'Telerik.Web.UI.RadListBoxItemCollection' in Assembly 'Telerik.Web.UI, Version=2013.2.717.40, Culture=neutral, PublicKeyToken=121fae78165ba3d4' is not marked as serializable.] System.Runtime.Serialization.FormatterServices.InternalGetSerializableMembers(RuntimeType type) +9476053 System.Runtime.Serialization.FormatterServices.GetSerializableMembers(Type type, StreamingContext context) +247 System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitMemberInfo() +160 System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder) +491 System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.Serialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder) +54 System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck) +542 System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boolean fCheck) +133 System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph) +13 System.Web.UI.ObjectStateFormatter.SerializeValue(SerializerBinaryWriter writer, Object value) +3113[ArgumentException: Error serializing value 'Telerik.Web.UI.RadListBoxItemCollection' of type 'Telerik.Web.UI.RadListBoxItemCollection.'] System.Web.UI.ObjectStateFormatter.SerializeValue(SerializerBinaryWriter writer, Object value) +3428 System.Web.UI.ObjectStateFormatter.Serialize(Stream outputStream, Object stateGraph) +141 System.Web.UI.ObjectStateFormatter.Serialize(Object stateGraph) +57 System.Web.UI.ObjectStateFormatter.System.Web.UI.IStateFormatter.Serialize(Object state) +4 System.Web.UI.Util.SerializeWithAssert(IStateFormatter formatter, Object stateGraph) +37 System.Web.UI.HiddenFieldPageStatePersister.Save() +79 System.Web.UI.Page.SavePageStateToPersistenceMedium(Object state) +108 System.Web.UI.Page.SaveAllState() +315 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2839 --------------------------------------------------------------------------------Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1016