序列化异常

请问出现下面的序列化异常是什么原因？Spread for ASP.NET 7.0

--------- 例外情報 ---------
System.IndexOutOfRangeException: インデックスが配列の境界外です。
   場所 System.Web.UI.ObjectStateFormatter.SerializeValue(SerializerBinaryWriter writer, Object value)
   場所 System.Web.UI.ObjectStateFormatter.Serialize(Stream outputStream, Object stateGraph)
   場所 FarPoint.Web.Spread.FpSpread.SaveViewState()
   場所 System.Web.UI.Control.SaveViewStateRecursive(ViewStateMode inheritedMode)
   場所 System.Web.UI.Control.SaveViewStateRecursive(ViewStateMode inheritedMode)
   場所 System.Web.UI.Control.SaveViewStateRecursive(ViewStateMode inheritedMode)
   場所 System.Web.UI.Control.SaveViewStateRecursive(ViewStateMode inheritedMode)
   場所 System.Web.UI.Control.SaveViewStateRecursive(ViewStateMode inheritedMode)
   場所 System.Web.UI.Control.SaveViewStateRecursive(ViewStateMode inheritedMode)
   場所 System.Web.UI.Control.SaveViewStateRecursive(ViewStateMode inheritedMode)
   場所 System.Web.UI.Page.SaveAllState()
   場所 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   --- 追加情報 ---