error occurred while work with excel files with multi thread

In Asp.net When working with multi threading via Excel Interop using the below code:

Public Class ImportService
Public Function ImportsFiles(ByVal files as list(Of String))
Dim rowEffect As Integer = 0
For j as Integer=0 to files.Count-1
dim fileAddress=files(j)
Dim app As New Application
Dim Wbook As Workbook

Try
    Wbook = app.Workbooks.Open(fileAddress, [ReadOnly]:=True)
    For i As Integer = 1 To Wbook.Sheets.Count
        If Not Wbook.Sheets(i).Name.ToString.ToLower.Contains("partial read of load profile") Then
            Dim con As New System.Data.OleDb.OleDbConnection("provider=Microsoft.ACE.OLEDB.12.0; Data Source=" & fileAddress & "; Extended Properties=""Excel 12.0 Xml;HDR=No;IMEX=1"";")
            Dim cmd As New OleDbCommand
            Dim s As String = "SELECT * FROM [" & Wbook.Sheets(i).Name & "$]"
            cmd.CommandText = s
            cmd.Connection = con
            Dim da As New OleDbDataAdapter
            da.SelectCommand = cmd
            Dim dt As New System.Data.DataTable
            da.Fill(dt)
            Dim err As New Dictionary(Of String, String)
            Dim fileDate As String = Wbook.Sheets(i).Name.ToString.Trim.Replace(" ", "/")
            rowEffect += InsertLps(Path.GetFileName(fileAddress), fileDate, dt.Rows, err)
            dt.Dispose()
            da.Dispose()
            con.Dispose()
            cmd.Dispose()
        End If
        ReleaseCOMObject(Wbook.Sheets(i))
        Next
    Wbook.Close(SaveChanges:=False)
Catch ex As Exception
    summary.Add(fileAddress, ex.Message)
Finally
    GC.Collect()
    GC.WaitForPendingFinalizers()
    GC.Collect()
    GC.WaitForPendingFinalizers()
    If app.Workbooks IsNot Nothing Then
        For Each wb In app.Workbooks
            For Each ws In wb.Worksheets
                ReleaseCOMObject(ws)
            Next
            wb.Close(False)
            ReleaseCOMObject(wb)
        Next
    End If
    app.Workbooks.Close()
    app.Quit()
    ReleaseCOMObject(app)
    GC.WaitForFullGCComplete()
Next
End Function
End Class

An error occurs:

Transition into COM context 0x946d20 for this RuntimeCallableWrapper failed with the following error: The object invoked has disconnected from its clients. (Exception from HRESULT: 0x80010108 (RPC_E_DISCONNECTED)). This is typically because the COM context 0x946d20 where this RuntimeCallableWrapper was created has been disconnected or it is busy doing something else. Releasing the interfaces from the current COM context (COM context 0x946c68). This may cause corruption or data loss. To avoid this problem, please ensure that all COM contexts/apartments/threads stay alive and are available for context transition, until the application is completely done with the RuntimeCallableWrappers that represents COM components that live inside them.

i'm trying to work with Quartz.net and more triggers do job in background. when 2 trrigger start job by this code:

Public Class ImportJob
Implements IJob
Public Sub Execute(context As IJobExecutionContext) Implements IJob.Execute
    Dim importHelpers As New ImportFilesHelpers
    Dim exts As New List(Of String)
    exts.Add(".xls")
    Dim files = importHelpers.GetFiles(ImportFilesHelpers.BaseAssress, exts)
    Dim import = New ImportService()
    import.ImportsFiles(files)
End Sub
End Class

Following Error Acoures in This Line

Dim fileDate As String = Wbook.Sheets(i).Name.ToString.Trim.Replace(" ", "/")