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OpenFileDialog error

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Last Modified: 2012-05-09
I have frmMain that opens frmPicture via a

dim frmPicture as New frmPicture
frmPicture.show()

button click.

On frmPicture I have a button that attempts to open a dialog box via
Me.OpenFileDialog.ShowDialog()
and I get a memory error shown below:

System.AccessViolationException was unhandled
  Message="Attempted to read or write protected memory. This is often an indication that other memory is corrupt."
  Source="System.Windows.Forms"
  StackTrace:
       at System.Windows.Forms.FileDialogNative.IFileDialog.Show(IntPtr parent)
       at System.Windows.Forms.FileDialog.RunDialogVista(IntPtr hWndOwner)
       at System.Windows.Forms.FileDialog.RunDialog(IntPtr hWndOwner)
       at System.Windows.Forms.CommonDialog.ShowDialog(IWin32Window owner)
       at System.Windows.Forms.CommonDialog.ShowDialog()
       at safetyLog.frmPicture.cmdSelect_Click(Object sender, EventArgs e) in C:\Users\VSL\Desktop\TroyerProject\safetyLog\safetyLog\frmPicture.vb:line 15
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(ApplicationContext context)
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
       at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
       at safetyLog.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81
       at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()

Any ideas on what is going on?  If I put an OpenFileDialog control and test button on frmMain and use the control it works fine.
Comment
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'Declaration

Public Function ShowDialog As Nullable(Of Boolean)
'Usage

Dim instance As OpenFileDialog
Dim returnValue As Nullable(Of Boolean)

returnValue = instance.ShowDialog()
Hope this help

Commented:
Try performing clean in the solution then rebuild it.

Sheldon LivingstonConsultant

Author

Commented:
Still no joy on this problem.
Sheldon LivingstonConsultant

Author

Commented:
Sometimes running the code will show the dialog box for a few seconds and then error out.  If I compile and run it on another machine there isn't an error.
Sheldon LivingstonConsultant

Author

Commented:
Essentially form A opens form B that opens form C.  

Using the openFileDialog control from C causes an error.
Consultant
Commented:
This one is on us!
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UNLOCK SOLUTION
On windows 7 (32 bit) had same problem when showing the openfiledialog from a modal form loaded for the second time with data from db in it. Solution was: do not allow autoupgrade of dialog.
Dim sfv As New System.Windows.Forms.SaveFileDialog
   With sfv
     .AutoUpgradeEnabled = False
     [...]

Cimperiali
On windows 7 (32 bit) had same problem when showing the SaveFileDialog from  a dot net windows form application (visual studio 2010, framework 4)  with data from access db (access 2010) in it. At first, solution appeared to be (but was not) : do not allow autoupgrade of dialog.
Dim sfv As New System.Windows.Forms.SaveFileDialog
   With sfv
     .AutoUpgradeEnabled = False
     [...]


But error came up again. Then I noticed it was apparently randomic till I realized it did not come out if I was able to show a saveFileDialog or an OpenfileDialog before loading any data from db.

Thus true workaround is: before load anything on the form you're going to show, display a dialog asking user to choose a path and file you *might* need after (arrrg!). After that, load data. Now your can let users, if needed, to choose path and file with dialog again...

ie:
  Private Sub frmReport_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
     txtFilePathName.Text = "Export_" & Now.ToString("yyyy_MM_dd_HH_mm_ss", CultureInfo.GetCultureInfo("it-It")) & ".csv"
     txtFilePathName.Text = GetSaveFileName(txtFilePathName.Text, ".csv", "Choose a csv File to save exported data", "csv |*.csv|All |*.*")
     'now load data in forms, where you can also have a button to call again the GetSaveFileName
[...]

Private Function GetSaveFileName(ByVal fileName As String,
                                    ByVal defaultExtension As String,
                                   ByVal title As String,
                                   ByVal filter As String) As String
        Dim sfv As New System.Windows.Forms.SaveFileDialog
        With sfv
            .RestoreDirectory = True
            .AddExtension = True
            .DefaultExt = defaultExtension
            .FileName = fileName
            .Title = title
            .Filter = filter
            .CheckPathExists = True
            .OverwritePrompt = True
            .ShowHelp = False

            If (.ShowDialog = DialogResult.OK) Then
                fileName = .FileName
            End If
        End With
        Return fileName
    End Function

Cimperiali

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