Dropbox error using upload session - vb.net

Question

This is the modified code about uploadsession soo at small size file it working like a charm but when I try larger file like 5mb up. The following error keep showing up :
+$exception {"lookup_failed/closed/..."} System.Exception {Dropbox.Api.ApiException}
Private Async Sub UploadToolStripMenuItem2_Click(sender As Object, e As EventArgs) Handles UploadToolStripMenuItem2.Click
Dim C As New OpenFileDialog
C.Title = "Choose File"
C.Filter = "All Files (*.*)|*.*"
If C.ShowDialog = Windows.Forms.DialogResult.OK Then
Dim fileinfos = Path.GetFileName(C.FileName)
Dim filetempat = Path.GetFullPath(C.FileName)
Dim tempat As String = direktori.Text & "/" & fileinfos
Await Upload(filetempat, tempat)
End If
End Sub
Async Function Upload(localPath As String, remotePath As String) As Task
Const ChunkSize As Integer = 4096 * 1024
Using fileStream = File.Open(localPath, FileMode.Open)
If fileStream.Length <= ChunkSize Then
Await A.Files.UploadAsync(remotePath, body:=fileStream)
Else
Await Me.ChunkUpload(remotePath, fileStream, ChunkSize)
End If
End Using
End Function
Private Async Function ChunkUpload(path As [String], stream As FileStream, chunkSize As Integer) As Task
Dim numChunks As Integer = CInt(Math.Ceiling(CDbl(stream.Length) / chunkSize))
Dim buffer As Byte() = New Byte(chunkSize - 1) {}
Dim sessionId As String = Nothing
For idx As Integer = 0 To numChunks - 1
Dim byteRead = stream.Read(buffer, 0, chunkSize)
Using memStream = New MemoryStream(buffer, 0, byteRead)
If idx = 0 Then
Dim result = Await A.Files.UploadSessionStartAsync(True, memStream)
sessionId = result.SessionId
kondisi.Text=byteRead
Else
Dim cursor = New UploadSessionCursor(sessionId, CULng(CUInt(chunkSize) * CUInt(idx)))
If idx = numChunks - 1 Then
Dim fileMetadata As FileMetadata = Await A.Files.UploadSessionFinishAsync(cursor, New CommitInfo(path), memStream)
MessageBox.Show("Upload Complete")
Console.WriteLine(fileMetadata.PathDisplay)
Else
Await A.Files.UploadSessionAppendV2Async(cursor, True, memStream)
MessageBox.Show("Upload Failed")
End If
End If
End Using
Next
End Function
okay now its fixed, but when i got home, and try this code at my home,i got error, is this method are affected by slow internet connection ?.cause my campus have a decent speed.
this is the error message
+$exception {"Cannot access a disposed object.\r\nObject name: 'System.Net.Sockets.Socket'."} System.Exception {System.ObjectDisposedException}
this Cannot obtain value of local or argument '<this>' as it is not available at this instruction pointer, possibly because it has been optimized away. System.Net.Sockets.Socket
asyncResult Cannot obtain value of local or argument 'asyncResult' as it is not available at this instruction pointer, possibly because it has been optimized away. System.IAsyncResult
errorCode Cannot obtain value of local or argument 'errorCode' as it is not available at this instruction pointer, possibly because it has been optimized away. System.Net.Sockets.SocketError
this error window i got
A first chance exception of type 'System.ObjectDisposedException' occurred in System.dll
Additional information: Cannot access a disposed object.

Answer 1

This Closed error indicates you can't continue uploading to the upload session because it's already been closed.
The UploadSessionStartAsync and UploadSessionAppendV2Async both take a bool parameter called close, which closes the session.
You're always setting that to True when you call those, closing the sessions. You shouldn't close a session until you're finished uploading data for it.