System.UnauthorizedAccessException (Access to the path denied) Error

[web2k6]

Hello,

I'm building an application that copies/downloads new txt file from a mapped network drive (sFTP site) to a local folder triggered by timer.

The application will run fine for hours and randomly gets an error message: "Access to the path 'G:\SourcePath' is denied"

Error message:

************** Exception Text **************
System.UnauthorizedAccessException: Access to the path 'G:\SourcePath' is denied.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileSystemEnumerableIterator`1.CommonInit()
   at System.IO.FileSystemEnumerableIterator`1..ctor(String path, String originalUserPath, String searchPattern, SearchOption searchOption, SearchResultHandler`1 resultHandler, Boolean checkHost)
   at System.IO.Directory.GetFiles(String path, String searchPattern, SearchOption searchOption)
   at Test1.Form1.CopyFiles()
   at Test1.Form1.tmrCountdown_Tick(Object sender, EventArgs e)
   at System.Windows.Forms.Timer.OnTick(EventArgs e)
   at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

I'm having trouble figuring this out why it keeps on happening..

Here is my code:

Private Sub CopyFiles()

        DISPLAYINFO("Checking for new files to process...")

        Dim sourcePath As String
        Dim destPath As String

        sourcePath = "G:\SourcePath\"
        destPath = "C:\test\DestinationPath\"

        Dim files() As String = Directory.GetFiles(sourcePath, "*.TXT", SearchOption.TopDirectoryOnly)
        Dim x As Integer

            If files.Count > 2 Then
                Debug.Print(files.Count)
            End If

            For x = 0 To files.Count - 1

                Dim sourceFile As String = Nothing
                Dim destFile As String = Nothing

                sourceFile = files(x)
                destFile = destPath & Path.GetFileName(sourceFile)

                strFileName.Text = Path.GetFileName(sourceFile)
                       
                    tmrCountdown.Enabled = False

                    If File.Exists(destFile) = True Then
                        DISPLAYINFO(Path.GetFileName(sourceFile) & " already exists.. Skipping")
                                              GoTo NextFile
                    Else
                        Try
                        File.Copy(sourceFile, destFile, True)
                        File.SetAttributes(destFile, FileAttributes.Normal)

                        DISPLAYINFO(Path.GetFileName(sourceFile) & " download complete..")
  
                        Catch ex As Exception
                            DISPLAYINFO("Failed to copy file from:" & vbCrLf & sourceFile & vbCrLf & "to" & vbCrLf & destFile)                            
                            GoTo NextFile
                        End Try

                    End If
      
NextFile:
            Next
			
			tmrCountdown.Enabled = True
    End Sub

Here is the timer code:

 Private Sub tmrCountdown_Tick(sender As Object, e As EventArgs) Handles tmrCountdown.Tick

        Dim GDrive As String = "G:\SourcePath\"

        If Directory.Exists(GDrive) Then
            CopyFiles()
        Else
            DISPLAYINFO("Network drive disconnected...")
        End If

    End Sub

TIA for looking and for your help!

[Shaggy Hiker]

If you were to leave it running, will it then start working again, or is it the case that once it fails it always fails?

The reason I ask is because there are a variety of network things that could cause this, so rather than preventing it, you might want to think about how to recover from it. If you simply trap the exception and either log it, or even ignore it, if the program then starts working again, that may be good enough. After all, even if you identify this particular problem, others network issues could arise that would result in the exact same exception for a different reason. So, perhaps noting that it is down is enough, or logging failures, or something like that.

[web2k6]

Hi Shaggy thanks for your input!

It will still keep on running. It bugs the heck out of me when leaving it overnight and checking in the morning with the big annoying error message box on your screen.

Is there a way to disable that? I tried doing regedits and jit settings on debug options but it doesn't seem to work.

Do you have any suggestions on what & where to write the code for the issues you've mentioned or how to trap the exception? I'm still a noob code writer.

As I've tried to check if the mapped network drive exists logic but it doesn't seem to be the issue.

[Shaggy Hiker]

It may be enough to wrap your call to CopyFiles in an exception handler.

The exception seems likely to be thrown by this line:

Dim files() As String = Directory.GetFiles(sourcePath, "*.TXT", SearchOption.TopDirectoryOnly)


if the path isn't accessible. You might wrap just that line in an exception handler, but there appear to be other things in CopyFiles. What you don't want is to trap the error in one place only to have it move. It seems like all of Copy Files can succeed or fail, so wrapping that call in an exception handler might be the best and easiest solution.