[Solved] ASP.Net Error: Unable to cast object of type System.DBNull to type System.Byte

I am getting error

An exception of type 'System.InvalidCastException' occurred in SMIS2022WEB.dll but was not handled in user code

Additional information: Unable to cast object of type 'System.DBNull' to type 'System.Byte[]'.

error comes here

Private Shared Function GetData(ByVal cmd As SqlCommand, ByVal pageIndex As Integer) As DataSet
    Dim strConnString As String = ConfigurationManager.ConnectionStrings("SMIS2022ConnectionString").ConnectionString
    Using con As SqlConnection = New SqlConnection(strConnString)
        Using sda As SqlDataAdapter = New SqlDataAdapter()
            cmd.Connection = con
            sda.SelectCommand = cmd
            Using ds As DataSet = New DataSet()
                sda.Fill(ds, "Files")
                Dim dt As DataTable = New DataTable("Pager")
                dt.Columns.Add("PageIndex")
                dt.Columns.Add("PageSize")
                dt.Columns.Add("RecordCount")
                dt.Rows.Add()
                dt.Rows(0)("PageIndex") = pageIndex
                dt.Rows(0)("PageSize") = PageSize
                dt.Rows(0)("RecordCount") = cmd.Parameters("@RecordCount").Value
                ds.Tables("Files").Columns.Add("Image")
                For i As Integer = 0 To ds.Tables("Files").Rows.Count - 1
 
                    If Not IsDBNull(CType(ds.Tables("Files").Rows(i)("Photo"), Byte())) Then
                        Dim imgBytes As Byte() = CType(ds.Tables("Files").Rows(i)("Photo"), Byte())
                        Dim base64String As String = Convert.ToBase64String(imgBytes, 0, imgBytes.Length)
                        ds.Tables("Files").Rows(i)("Image") = "data:image/png;base64," & base64String
                    End If
 
                Next
 
                ds.Tables.Add(dt)
                Return ds
            End Using
        End Using
    End Using
End Function