I inherited an undocumented VB.NET application in order to provide support for some users. I am very new to .NET. The application has a welcome form, that is accessed after logging in, with menus that open other forms.
One of these form (supposed to print some labels) throws a ObjectDisposedException error and crashes.
I copied the stack trace (or at least what I think it is) and need to understand what is caused the crash.
For now my research led me to understand FrmMenu is causing the error since it is not disposed properly, but I am stuck there.
What should I understand by this trace?
Message=Cannot access a disposed object.
Object name: 'FrmMenu'.
Source=mscorlib
ObjectName=FrmMenu
StackTrace:
Server stack trace:
at System.Windows.Forms.Control.CreateHandle()
at System.Windows.Forms.Form.CreateHandle()
at PrjInv.FrmMenu.applicationIdle_TickAsync(Object sender, TickEventArgs e) in C:\TFSSolution\FrmMenu.vb:line 1805
at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs)
at System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink)
Exception rethrown at [0]:
at System.Runtime.Remoting.Proxies.RealProxy.EndInvokeHelper(Message reqMsg, Boolean bProxyCase)
at System.Runtime.Remoting.Proxies.RemotingProxy.Invoke(Object NotUsed, MessageData& msgData)
at System.EventHandler`1.EndInvoke(IAsyncResult result)
at Winforms.Components.ApplicationIdle.OnTickAsyncCompleted(IAsyncResult asyncResult) in C:\Users\User.User-PC\Desktop\Application Idle Solution\Winforms.Components\ApplicationIdle.cs:line 822
at System.Runtime.Remoting.Messaging.AsyncResult.SyncProcessMessage(IMessage msg)
at System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink)
at System.Runtime.Remoting.Proxies.AgileAsyncWorkerItem.ThreadPoolCallBack(Object o)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)
Reading from comments, I get these 2 functions.
At line 1805:
Private Sub applicationIdle_TickAsync(sender As Object, e As TickEventArgs)
If Not Me.IsHandleCreated Then
Me.CreateHandle()
End If
BeginInvoke(New MethodInvoker(Sub() applicationIdle_Tick(sender, e)))
End Sub
And oddly enough
Private Sub applicationIdle_Tick(sender As Object, e As TickEventArgs)
If e.IsWarnPeriod Then
' UpdateTimeDisplays(warnColour)
Else
' UpdateTimeDisplays(normalColour)
End If
End Sub
Yes, the code is commented!!! What should I understand?
Related
IT;S VB.NET not C# and i don't know how to exchange source from C# to VB.NET, THANKS
I want to get all paths from all running processes.
This is my source so far:
For Each p As Process In Process.GetProcesses
Try
ListBox1.Items.Add(p.MainModule.FileName.ToString)
Catch ex As Exception
RichTextBox1.Text = ex.Message
End Try
Next
But I can't get all path folders of the running processes.
If I examine the ex.Message, the response is like this
Unable to enumerate the process modules.
But if I not using ex.Message, the response is like this :
System.ComponentModel.Win32Exception was unhandled
ErrorCode=-2147467259
HResult=-2147467259
Message=A 32 bit processes cannot access modules of a 64 bit process.
NativeErrorCode=299
Source=System
StackTrace:
at System.Diagnostics.NtProcessManager.GetModuleInfos(Int32 processId, Boolean firstModuleOnly)
at System.Diagnostics.NtProcessManager.GetFirstModuleInfo(Int32 processId)
at System.Diagnostics.Process.get_MainModule()
at Anti_Cheat.Form1.Button6_Click(Object sender, EventArgs e) in c:\users\adiyatma\documents\visual studio 2012\Projects\Anti Cheat\Anti Cheat\Form1.vb:line 40
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(IntPtr 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 Anti_Cheat.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81
at System.AppDomain._nExecuteAssembly(RuntimeAssembly 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.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:
Can anyone help me?
Take a look at the so-question How to get the full path of running process?
Instead of
ListBox1.Items.Add(p.MainModule.FileName.ToString)
try
ListBox1.Items.Add(p.Modules(0).FileName.ToString)
Edit:
Have you tried to evaluate the property of different processes directly? Maybe there is a certain process you cannot access, resulting in the error described.
You can try to iterate trough the processes one by one by creating the following loop:
For Each p As System.Diagnostics.Process In System.Diagnostics.Process.GetProcesses()
Try
Console.WriteLine(p.Modules(0).FileName)
Catch ex As Exception
Console.WriteLine(String.Format("{0}: Error - {1}", p.ProcessName, ex.Message))
End Try
Next
By doing so, you should be able to determine the processes you're not allowed to access and get a couple of processes you should be able to experiment with.
Mate the problem is obvious, you are targeting 32-bit but are testing your app on a computer that has 64-bit installed system, that's why you get the error.
Message=A 32 bit processes cannot access modules of a 64 bit process.
to fix this issue you should make the target 64-bit, there IS NO SOLUTION for this...
if you know the famous procexp (sysinternals) it has two separate application, when the system is 32-bit it lauches an instance of 32-bit, but when it is 64-bit it lauches another separate process for the system...
so if you want to deal with this issue, you have to make two instances for system compability,
Hope this is helpful
I'm working on a directory Project where in when the program is not being use or idle for 3 minutes, a form that act as stand-by screen that plays a video will show (I use AxWindowsMediaPlayer). By clicking anywhere in the form, the stand-by screen will close and will be back to the main form.
The program works fine but SOMETIMES during the closing of stand-by screen form, the application crashes with the error:
AccessViolationException was unhandled. Attempted to read or write
protected memory. This is often an indication that other memory is
corrupt.
and this is the complete error detail:
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.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr 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.RunDialog(Form form)
at System.Windows.Forms.Form.ShowDialog(IWin32Window owner)
at System.Windows.Forms.Form.ShowDialog()
at BuildingDirectory.main.tmrTime_Tick(Object sender, EventArgs e) in C:\Users\pc\Documents\Visual Studio 2010\Projects\testing\BuildingDirectory\BuildingDirectory\main.vb:line 128
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.TimerNativeWindow.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(IntPtr 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 BuildingDirectory.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81
at System.AppDomain._nExecuteAssembly(RuntimeAssembly 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, Boolean ignoreSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:
The weird thing is, the line of code where the error is pointing, is enclosed in try catch block specifically catching AccessViolationException(it was exception before but still encountered the problem):
Private Sub tmrTime_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrTime.Tick
Try
lblTime.Text = TimeOfDay
If standby = 2 Then
standby += 1
standByScreen.ShowDialog() ---> this is where the error is pointing to
Else
standby += 1
End If
Catch ex As AccessViolationException
MessageBox.Show(ex.ToString)
End Try
End Sub
Please help me, thank you
This might be due to early binding of the standByScreen variable. Note that the error is caused due to the System.Windows.Forms class
Try:
Dim stndByScreen As Object
stndByScreen = standByScreen
stndByScreen.ShowDialog()
instead of directly using standByScreen
When I load up a XAML file in the designer I get the below exception and then I have to kill VS 2012 from the process manager. Any ideas on work arounds?
Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteException
Object reference not set to an instance of an object.
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOutSynchronous(Action action, Int32 targetApartmentId, WaitHandle aborted, WaitHandle timeoutSignal)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOut(Action action, Int32 targetApartmentId, WaitHandle aborted, CallSynchronizationMode syncMode, WaitHandle timeoutSignal)
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TValue](RemoteHandle`1 targetObject, Action action, CallSynchronizationMode syncMode)
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TResult,TValue](RemoteHandle`1 targetObject, Func`2 func, CallSynchronizationMode syncMode)
at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalHostTextBufferSynchronizer.get_IsReadOnly()
at Microsoft.Expression.DesignHost.DesignerTextBufferSynchronizer.get_IsReadOnly()
at Microsoft.Expression.DesignHost.DesignerTextBuffer.get_IsReadOnly()
at Microsoft.Expression.DesignSurface.Documents.TextBuffer.get_IsReadOnly()
at Microsoft.Expression.DesignSurface.Documents.SceneDocument.get_IsReadOnly()
at Microsoft.Expression.DesignSurface.Documents.SceneDocument.get_IsUndoTargetReadOnly()
at Microsoft.Expression.DesignSurface.Selection.SelectionSet`2.SetSelectionWithUndo(String description, ListOfT newSelection, T newPrimarySelection)
at Microsoft.Expression.DesignSurface.Selection.SceneNodeSelectionSet.SetSelectionWithUndo(String description, SceneNodeOrderedCollection newSelection, SceneNode newPrimarySelection)
at Microsoft.Expression.DesignSurface.Selection.SelectionSet`2.ExtendSelection(T selectionToExtend)
at Microsoft.Expression.DesignSurface.ViewModel.SceneViewModel.SelectNodes(ICollection`1 nodes)
at Microsoft.Expression.DesignSurface.View.SceneView.SelectionSynchronizer.OnCaretPositionChangedTimeoutTimerTick(TextEditorContext textEditor)
at Microsoft.Expression.DesignSurface.View.SceneView.SelectionSynchronizer.SynchronizeSceneToMarkup(TextEditorContext textEditor)
at Microsoft.Expression.DesignSurface.View.SceneView.TextEditor_CaretPositionChanged(Object sender, EventArgs e)
at Microsoft.Expression.DesignSurface.TextEditorContext.CaretPositionChangedPipe(Object sender, EventArgs args)
at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalEvent`2.<>c__DisplayClass12.<Invoke>b__10()
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.Invoke(Boolean waitingInExternalCall)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.InvokeCall(Call call)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.ProcessQueue(CallQueue queue)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.ProcessInboundQueue(Int32 identity)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.ProcessMessage(Int32 msg, IntPtr wParam, Boolean elevatedQuery, Boolean& handled)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.OnWindowMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at Microsoft.Expression.DesignHost.Isolation.Remoting.MessageOnlyHwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
at System.Windows.Threading.Dispatcher.Run()
at System.Windows.Application.RunDispatcher(Object ignore)
at System.Windows.Application.RunInternal(Window window)
at System.Windows.Application.Run(Window window)
at System.Windows.Application.Run()
at Microsoft.Expression.DesignHost.Isolation.IsolationProcess.RunApplication()
at Microsoft.Expression.DesignHost.Isolation.IsolationProcess.<>c__DisplayClass2.<Main>b__0()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteException
Object reference not set to an instance of an object.
Server stack trace:
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalIn(Action action, Int32 targetApartmentId)
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn(IRemoteObject targetObject, Action action)
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn[TResult](IRemoteObject targetObject, Func`1 func)
at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteHostTextBufferSynchronizer.get_IsReadOnly()
at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg)
Exception rethrown at [0]:
at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
at Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteHostTextBufferSynchronizer.get_IsReadOnly()
at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalHostTextBufferSynchronizer.<get_IsReadOnly>b__8(IRemoteHostTextBufferSynchronizer hs)
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass4`2.<MarshalOut>b__3()
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()
Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteException
Object reference not set to an instance of an object.
at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteHostTextBufferSynchronizer.<get_IsReadOnly>b__7()
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass16`1.<MarshalIn>b__15()
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()
I know this one is a bit old but I had a similar problem in VS2013, found a clue from an MSDN article and checked the event viewer for exceptions, look for XDesProc.exe.
The problem was an out of date driver for my graphics card.
Once that was updated all started working again
It might help someone
I have a form where the user can first scan to a bitmap. When scan is done, and the bitmap is loaded, I have 4 text boxes that are then enabled. Next to each text box, I have a button called "Cut from image". When the user clicks the button, they can click and drag in the bitmap to get the selected text using MODI.
This works perfect except for one annoying bug: When I click a "Cut from image" button and drag a square, it gets the information nicely to the text box. Then, if i click to the next text box, it goes very well, but if I use the tab key to leave the field, I get a "Parameter is not valid" ArgumentException and it does not show any help for where in the code the crash is made. I can tab around in the form with no problems at all, but once the bitmap is scanned, it crashes like 9 out of 10 times when I use the tab key.
I tried to override the tab key (just for debugging) using this:
Protected Overrides Function ProcessTabKey(ByVal forward As Boolean) As Boolean
MsgBox("TAB is currently disabled!")
Return False 'Tried True as well, just in case
End Function
...but it still crashes.
Any suggestions about what's wrong? Since I don't know where to begin debugging I can't tell what code to show.
EDIT 1
Here is the stack trace for the ArgumentException that gets thrown:
at System.Drawing.Image.get_Width()
at System.Drawing.Image.get_Size()
at System.Windows.Forms.PictureBox.ImageRectangleFromSizeMode(PictureBoxSizeMode mode)
at System.Windows.Forms.PictureBox.OnPaint(PaintEventArgs pe)
at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer)
at System.Windows.Forms.Control.WmPaint(Message& m)
at System.Windows.Forms.Control.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(IntPtr 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 Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
at ORC_Testing.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81
at System.AppDomain._nExecuteAssembly(RuntimeAssembly 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, Boolean ignoreSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
EDIT 2
Here is how I'm scanning/loading the image:
Dim filename As Collection
filename = TwainHandler.ScanImages("c:\scan\", "tif")
Dim ScannedFile As Image = Image.FromFile(filename(1))
PictureBox1.Image = ScannedFile
PictureBox1.Width = ScannedFile.Width
' etc.
Your problem is likely that, at some point, you are calling the Dispose method on one of your Image objects. When you call Image.Dispose, it deletes the underlying image data from memory, so the Image object still exists, but is invalid because it no longer contains an actual image. When you set the PictureBox.Image property to a loaded Image object, the PictureBox control assumes that the Image object will remain valid so that it can reuse it later any time the control needs to repaint itself to the screen. For instance:
Dim myImage As Image = Image.FromFile("file path")
PictureBox1.Image = myImage
PictureBox1.Refresh() ' This works
myImage.Dispose()
PictureBox1.Refresh() ' This throws an exception because it tries to access the disposed Image object
The PictureBox control will automatically dispose of the image for you when it is disposed, so you don't need to worry about disposing it yourself. The only time you should be disposing your images is when you are not giving them to any other objects for later use.
Here is my solution, somebody could use it, even though the question is old.
Dim myImage As Image = Image.FromFile("file path")
PictureBox1.Image = myImage.clone // Use clone to give a new copy not a reference of image
PictureBox1.Refresh() // This works
myImage.Dispose()
PictureBox1.Refresh() // This works also because we've a copy not reference
PictureBox1.Image = myImage.Clone
This way you are using a copy of the image so it does not matter what happens with the original
I am currently trying to make an existing VB.NET Project run. A null pointer exception is thrown in the WndProc message but the stack trace does not really give me anything. I can place a break point in the startup form's designer code but when I step through it triggers a NULL pointer exception via WndProc function. The upper methods seems to be Windows methods. The only clue I have is the Message parameter with Msg = 24 and WParam = 1. I think the HWnd = 5178884 does not help.
I am pasting the stack trace in case someone has any ideas.
Note: I masked the MyNamespace and MyBaseForm and MyFormA because the source code is proprietary. This runs in Visual Studio 2008 on .NET Framework 3.5
MyNamespace.Forms.MyBaseForm.WndProc(Message& m)\r\n
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)\r\n
System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)\r\n
System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)\r\n
System.Windows.Forms.SafeNativeMethods.ShowWindow(HandleRef hWnd, Int32 nCmdShow)\r\n
System.Windows.Forms.Control.SetVisibleCore(Boolean value)\r\n
System.Windows.Forms.Form.SetVisibleCore(Boolean value)\r\n
System.Windows.Forms.Control.set_Visible(Boolean value)\r\n
System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)\r\n
System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)\r\n
System.Windows.Forms.Application.Run(ApplicationContext context)\r\n
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()\r\n
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()\r\n
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)\r\n
MyFormA.My.MyApplication.Main(String[] Args)
17d14f5c-a337-4978-8281-53493378c1071.vb:Line 81\r\n
System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)\r\n
System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)\r\n
Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()\r\n
System.Threading.ThreadHelper.ThreadStart_Context(Object state)\r\n
System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)\r\n
System.Threading.ThreadHelper.ThreadStart()"
WM_SHOWWINDOW = 24
...not that it really helps.
It looks like the last bit of your code to be executed is line 81, I'd study that.
I just want to give another answer on how to know where the error came from even if the stack trace did not tell you anything (The actual problem why I asked what is WndProc 24). Just in case other people had the same problem too.
I used the Unhandled Exception via Debug > Exceptions menu on Visual Studio. See this link for detail.
Maintaining the point to C.Barlow as he answered the initial question.