asp.net - タイプ X のオブジェクトをタイプ X にキャストできません

Question

ユーザーはランダムに「タイプ「X」のオブジェクトをタイプ「X」にキャストできません」という例外エラーを受け取ります。この問題は 1 日に数回発生する場合があります。場合によっては、1 週間以上かかることもあります。

リスト「CurrentDetails」と「NextDetails」に「X」として入力するシリアル化されたオブジェクト（「X」）があります。テキスト変更イベントで、「CurrentDetails」の値をチェックし、その時点で例外が発生します。「型 X のオブジェクトを型 X にキャストできません」いくつかのコード サンプルを次に示します...

テキスト変更イベント (生データを表示するように編集)

Protected Sub txtPackaging_TextChanged(sender As Object, e As System.EventArgs) Handles txtPackaging.TextChanged
    If WarehouseManager.GetDeliveryStatus(CurrentSUPPDelivery.DeliveryNumber) > 60 Then
        'GETTIGN ERROR HERE Unable to cast object of type 'SUPPDelivery' to type 'SUPPDelivery' 
        'THROW ERROR
        SetErrorMessage("<b>REFRESH/BACK DETECTED!</b> <br/> Or, this item has already been packed. <br/> Please exit wave.")
        pnlItemDetails.Visible = False
        pnlCurrent.Visible = False
        pnlWaveDetails.Visible = False
    Else 'continue pick/pack
        btnProcessSingleItem_Click(sender, e)

    End If

End Sub

View State Object (生データを表示するように編集)

Private Property CurrentSUPPDelivery() As WarehouseManager.SUPPDelivery
    Get
        Return Me.ViewState("CurrentSUPPDelivery")
    End Get
    Set(ByVal value As WarehouseManager.SUPPDelivery)
        Me.ViewState("CurrentSUPPDelivery") = value
    End Set
End Property

txtChange イベントの IF ステートメントでエラーをスローしています。何か案は？

編集：生のスタックデータ....

スタック トレース: C:\Inetpub\lawsonwebapps\warehouse\mobile\SingleUnitPickPack.aspx.vb の Warehouse_SingleUnitPickPack.get_CurrentSUPPDelivery():107 行目 C:\Inetpub\lawsonwebapps\warehouse\ の Warehouse_SingleUnitPickPack.txtPackaging_TextChanged(Object sender, EventArgs e) mobile\SingleUnitPickPack.aspx.vb: System.Web.UI.WebControls.TextBox.OnTextChanged(EventArgs e) の行 249 System.Web.UI.WebControls.TextBox.RaisePostDataChangedEvent() の System.Web.UI.WebControls.TextBox .System.Web.UI.IPostBackDataHandler.RaisePostDataChangedEvent() で System.Web.UI.Page.RaiseChangedEvents() で System.Web.UI.Page.ProcessRequestMain (ブール値 includeStagesBeforeAsyncPoint、ブール値 includeStagesAfterAsyncPoint)

編集: "X" - Manager.CurrentDetails ... RAW 名:SUPPDelivery

<Serializable()> Public Class SUPPDelivery

        Private _DeliveryNumber As String
        Private _OrderNumber As String
        Private _OrderLine As String
        Private _TransactionType As String
        Private _PackedQty As String
        Private _PackageNumber As String
        Private _PackageMaterial As String
        Private _OrderLineSuffix As String
        Private _ItemNumber As String
        Private _ItemLocation As String

        Public Property DeliveryNumber() As String
            Get
                Return _DeliveryNumber
            End Get
            Set(ByVal value As String)
                _DeliveryNumber = value
            End Set
        End Property

        Public Property OrderNumber() As String
            Get
                Return _OrderNumber
            End Get
            Set(ByVal value As String)
                _OrderNumber = value
            End Set
        End Property

        Public Property OrderLine() As String
            Get
                Return _OrderLine
            End Get
            Set(ByVal value As String)
                _OrderLine = value
            End Set
        End Property

        Public Property TransactionType() As String
            Get
                Return _TransactionType
            End Get
            Set(ByVal value As String)
                _TransactionType = value
            End Set
        End Property

        Public Property PackedQty() As String
            Get
                Return _PackedQty
            End Get
            Set(ByVal value As String)
                _PackedQty = value
            End Set
        End Property

        Public Property PackageNumber() As String
            Get
                Return _PackageNumber
            End Get
            Set(ByVal value As String)
                _PackageNumber = value
            End Set
        End Property

        Public Property PackageMaterial() As String
            Get
                Return _PackageMaterial
            End Get
            Set(ByVal value As String)
                _PackageMaterial = value
            End Set
        End Property

        Public Property OrderLineSuffix() As String
            Get
                Return _OrderLineSuffix
            End Get
            Set(ByVal value As String)
                _OrderLineSuffix = value
            End Set
        End Property

        Public Property ItemNumber() As String
            Get
                Return _ItemNumber
            End Get
            Set(ByVal value As String)
                _ItemNumber = value
            End Set
        End Property

        Public Property ItemLocation() As String
            Get
                Return _ItemLocation
            End Get
            Set(ByVal value As String)
                _ItemLocation = value
            End Set
        End Property

    End Class