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Null Reference Exception after Forms.TabPageCollection.Remove() caexception is being hit very rarely during acceptance testing. Is this a known defect? Is there a workaround? Is it corrected in .NET 2.0? Problem: Very intermittent Null Reference Exception deep in Windows code after calling 'Forms.TabPageCollection.Remove' method Details: - Always occurs with stack frames mentioning "ParkingWindow" on the backtrace (see following). - Has been seen originating with Controls.Clear() method as well. - The same code path gets executed a great number of times without problems. Only very rarely does an exception get thrown. Given the difficulting in repeating the problem not much more is known about the circumstances. Stack Backtrace: Additional Info: System.NullReferenceException: Object reference not set to an instance of an object. at System.Windows.Forms.WndProc.Invoke(IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WmUpdateUIState(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ContainerControl.WndProc(Message& m) at System.Windows.Forms.ParkingWindow.WndProc(Message& m) at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ContainerControl.WndProc(Message& m) at System.Windows.Forms.ParkingWindow.WndProc(Message& m) at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, Int32 msg, Int32 wParam, Int32 lParam) at System.Windows.Forms.Control.SendMessage(Int32 msg, Int32 wparam, Int32 lparam) at System.Windows.Forms.Control.WmCreate(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef hInst, Object pvParam) at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef hInst, Object pvParam) at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) at System.Windows.Forms.Control.CreateHandle() at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) at System.Windows.Forms.Control.CreateControl() at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) at System.Windows.Forms.Control.AssignParent(Control value) at System.Windows.Forms.TabPage.AssignParent(Control value) at System.Windows.Forms.ControlCollection.Remove(Control value) at System.Windows.Forms.ControlCollection.Remove(Control value) at System.Windows.Forms.TabPageCollection.Remove(TabPage value) at <our application code> Possible reference found in Google search: - Webpage "Derived combo box controls in forms - MessageBox.Show breaks the control's message routing" indicates that derived ComboBox controls might be involved - that is possible in our situation. See http://www.tech-archive.net/Archive/DotNet/microsoft.public.dotnet.languages.vb.controls/2004-05/0170.html Thanks in advance for your assistance, Dave -- Dave Leach Agilent Technologies, Inc. Hi Dave,
I am sorry that I may not understand your scenario exactly. I have several questions here. 1. I know that your program is written in VS.NET 2003 wih C#. But you have mentioned a reference you found in Google search, which talks about using C# form in an MFC application. Is your program related to MFC? 2. You have mentioned the exception is raised after the call to 'System.Windows.Forms.TabPageCollection.Remove(TabPage value)'. Does the form has a TabControl on it? Could you please tell me what controls reside on the form and what operations you perform on the form before you encounter the exception? 3. Since the exception is very intermittent, is it possible that the exception is caused by other reasons, instead of the operation of deleting a tab page from the TabControl? For example, when the user deletes a tab page from the TabControl, the application receives a message and tries to access the controls on the deleted tab page. Sincerely, Linda Liu Microsoft Online Community Support ================================================== Get notification to my posts through email? Please refer to http://msdn.microsoft.com/subscriptions/managednewsgroups/default.aspx#notif ications. Note: The MSDN Managed Newsgroup support offering is for non-urgent issues where an initial response from the community or a Microsoft Support Engineer within 1 business day is acceptable. Please note that each follow up response may take approximately 2 business days as the support professional working with you may need further investigation to reach the most efficient resolution. The offering is not appropriate for situations that require urgent, real-time or phone-based interactions or complex project analysis and dump analysis issues. Issues of this nature are best handled working with a dedicated Microsoft Support Engineer by contacting Microsoft Customer Support Services (CSS) at http://msdn.microsoft.com/subscriptions/support/default.aspx. ================================================== This posting is provided "AS IS" with no warranties, and confers no rights. Linda,
In answer to your questions: 1. No, we are not using MFC, just .NET 1.1, C# and VS 2003. The reference is just one of many that can be found using a Google search on the keyword "ParkingWindow" and "exception". Note that Clive Dixon also replied to my post and has seen this problem as well. 2. Yes, the Form has a TabControl on it, which is why a tab page was being removed. The tab pages are added and removed from the TabControl depending on the user request. The tab pages contain a variety of controls. The type of controls on the tab pages are a mix of standard Label controls and controls derived from TextBox, ComboBox and ListView. I should also point out that we have also seen this problem recently where the stack backtrace does not include a reference to a TabControl. 3. Yes, it is possible, but it seems unlikely since the stack backtrace leaves our code and enters the MS code at the Remove call and proceeds to the point of the null reference exception. If you would do some research you will find that this problem manifests itself in several ways, but always seems to involve the ParkingWindow. Several people have posted queries to different sites related to this issue. We are attempting to find a way to reliably reproduce the problem, but I don't hold out much hope of that given other people's experiences. So again, is this a known problem? Is it always related to the ParkingWindow? Is there a work-around? Does .NET 2.0 resolve the issue? Thanks, Dave -- Show quoteDave Leach Agilent Technologies, Inc. "Linda Liu [MSFT]" wrote: > Hi Dave, > > I am sorry that I may not understand your scenario exactly. I have several > questions here. > > 1. I know that your program is written in VS.NET 2003 wih C#. But you have > mentioned a reference you found in Google search, which talks about using > C# form in an MFC application. Is your program related to MFC? > > 2. You have mentioned the exception is raised after the call to > 'System.Windows.Forms.TabPageCollection.Remove(TabPage value)'. Does the > form has a TabControl on it? Could you please tell me what controls reside > on the form and what operations you perform on the form before you > encounter the exception? > > 3. Since the exception is very intermittent, is it possible that the > exception is caused by other reasons, instead of the operation of deleting > a tab page from the TabControl? For example, when the user deletes a tab > page from the TabControl, the application receives a message and tries to > access the controls on the deleted tab page. > > > Sincerely, > Linda Liu > Microsoft Online Community Support > > ================================================== > Get notification to my posts through email? Please refer to > http://msdn.microsoft.com/subscriptions/managednewsgroups/default.aspx#notif > ications. > > Note: The MSDN Managed Newsgroup support offering is for non-urgent issues > where an initial response from the community or a Microsoft Support > Engineer within 1 business day is acceptable. Please note that each follow > up response may take approximately 2 business days as the support > professional working with you may need further investigation to reach the > most efficient resolution. The offering is not appropriate for situations > that require urgent, real-time or phone-based interactions or complex > project analysis and dump analysis issues. Issues of this nature are best > handled working with a dedicated Microsoft Support Engineer by contacting > Microsoft Customer Support Services (CSS) at > http://msdn.microsoft.com/subscriptions/support/default.aspx. > ================================================== > > This posting is provided "AS IS" with no warranties, and confers no rights. > > Hi Dave,
Thank you for your prompt response and detailed explanation. I have searched our inner data base and found a similar case in it. This case is solved by the hotfix 893005. You may visit the following link for the corresponding KB article: http://support.microsoft.com/default.aspx?scid=kb;en-us;893005 To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site: http://support.microsoft.com/contactus/?ws=support Hope this helps. Sincerely, Linda Liu Microsoft Online Community Support Linda,
The hotfix below does not apply to our situation. The hotfix deals with a situation where a form containing either a ToolTip or ErrorProvider control is closed and recreated. We do not use the ErrorProvider control at all and only one form in the entire program uses the ToolTip control and it is not closed until the program is exited. We see the NullReference exception usually following a container control clearing its list using the method ControlCollection.Remove() or ControlCollection.Clear(). Is there any item in your inner data base or KB that deals with a NullReference exception or Unhandled exception related to the combination of clearing a ControlCollection? How about exceptions related to the occurance of a ParkingWindow in the stack back trace? Dave -- Show quoteDave Leach Agilent Technologies, Inc. "Linda Liu [MSFT]" wrote: > Hi Dave, > > Thank you for your prompt response and detailed explanation. > > I have searched our inner data base and found a similar case in it. This > case is solved by the hotfix 893005. You may visit the following link for > the corresponding KB article: > > http://support.microsoft.com/default.aspx?scid=kb;en-us;893005 > > To resolve this problem immediately, contact Microsoft Product Support > Services to obtain the hotfix. For a complete list of Microsoft Product > Support Services telephone numbers and information about support costs, > visit the following Microsoft Web site: > > http://support.microsoft.com/contactus/?ws=support > > Hope this helps. > > > Sincerely, > Linda Liu > Microsoft Online Community Support > > Hi Dave,
Thank you for your prompt response. Sorry that I didn't clarify in my previous reply. The KB 893005 was addressing a case whose scenario was different from yours, but with similar symptoms(the call stack of this case when the exception occurs is the same as your program's). In that case, an object which is subclassed by the ToolTip can throw an exception if an error occurs while unsubclassing the control. The Framework wouldn't detect this situation correctly and could free the subclass procedure's memory while it was still set to be the control's window procedure. In addition, there're several cases recorded in our inner data base, whose scenarios are different, but with the similar symptoms as your program. They were all solved by the hotfix 893005. Please give hotfix 893005 a try and let me know if it works. Sincerely, Linda Liu Microsoft Online Community Support Dave,
Have you had any success with the below mentioned hotfix? I'm seeing the same stack trace (or at least a subset of it) resulting in either a NullReferenceException or in at least one case, an SEHException. Likewise, we're doing a lot of clearing of controls and think that is likely part of it. at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WmUpdateUIState(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ContainerControl.WndProc(Message& m) at System.Windows.Forms.ParkingWindow.WndProc(Message& m) at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) Mike Mayer, Autonomy etalk Show quote "Dave Leach" wrote: > We see the NullReference exception usually following a container control > clearing its list using the method ControlCollection.Remove() or > ControlCollection.Clear(). > > Is there any item in your inner data base or KB that deals with a > NullReference exception or Unhandled exception related to the combination of > clearing a ControlCollection? How about exceptions related to the occurance > of a ParkingWindow in the stack back trace? > > "Linda Liu [MSFT]" wrote: > > I have searched our inner data base and found a similar case in it. This > > case is solved by the hotfix 893005. Dave,
The phrase "parking window" and seeing CreateHandle in the stack gives me some ideas which may begin to help. I had a vaguely similar sort of problem a couple of years back which took me about 3 weeks to track down, eventually discovering a .NET 1.1 bug. There are certain scenarios in which a control on a form can be created with a temporary parent window called the "parking window", and in theory it gets reparented to the form later on. However there are certain circumstances in which it doesn't happen correctly, and control messages are still getting routed through this parking window. Furthermore there are some situations in which the parking window gets destroyed (in our case it was simply invoking a message box), and then the next time messages get sent to the control (and thus via the no-longer-existing parking window) it goes bang. I'll bet that something similar is going on with you. Do a search on "parking window" in microsoft.public.dotnet.framework.windowsforms and you'll see some of my postings on that issue and the workaround. (It's fixed in 2.0.) Show quote "Dave Leach" <babel@newsgroups.nospam> wrote in message news:D0BE86F8-8A55-468F-B1A8-0DEB187CDDB4@microsoft.com... >I am developing a Windows Forms based application using VS 2003 in C#. An > exception is being hit very rarely during acceptance testing. > > Is this a known defect? > Is there a workaround? > Is it corrected in .NET 2.0? > > Problem: Very intermittent Null Reference Exception deep in Windows code > after calling 'Forms.TabPageCollection.Remove' method > > Details: > - Always occurs with stack frames mentioning "ParkingWindow" on the > backtrace (see following). > - Has been seen originating with Controls.Clear() method as well. > - The same code path gets executed a great number of times without > problems. Only very rarely does an exception get thrown. Given the > difficulting in repeating the problem not much more is known about the > circumstances. > > Stack Backtrace: > Additional Info: System.NullReferenceException: Object reference not set > to > an instance of an object. > at System.Windows.Forms.WndProc.Invoke(IntPtr hWnd, Int32 msg, IntPtr > wParam, IntPtr lParam) > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > at System.Windows.Forms.Control.DefWndProc(Message& m) > at System.Windows.Forms.Control.WmUpdateUIState(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ContainerControl.WndProc(Message& m) > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > at System.Windows.Forms.Control.DefWndProc(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ContainerControl.WndProc(Message& m) > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > at System.Windows.Forms.Control.DefWndProc(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > at System.Windows.Forms.Control.DefWndProc(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, > Int32 msg, Int32 wParam, Int32 lParam) > at System.Windows.Forms.Control.SendMessage(Int32 msg, Int32 wparam, > Int32 lparam) > at System.Windows.Forms.Control.WmCreate(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 > x, > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, > HandleRef hInst, Object pvParam) > at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 > x, > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, > HandleRef hInst, Object pvParam) > at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) > at System.Windows.Forms.Control.CreateHandle() > at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) > at System.Windows.Forms.Control.CreateControl() > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.AssignParent(Control value) > at System.Windows.Forms.TabPage.AssignParent(Control value) > at System.Windows.Forms.ControlCollection.Remove(Control value) > at System.Windows.Forms.ControlCollection.Remove(Control value) > at System.Windows.Forms.TabPageCollection.Remove(TabPage value) > at <our application code> > > Possible reference found in Google search: > - Webpage "Derived combo box controls in forms - MessageBox.Show breaks > the control's message routing" indicates that derived ComboBox controls > might > be involved - that is possible in our situation. See > http://www.tech-archive.net/Archive/DotNet/microsoft.public.dotnet.languages.vb.controls/2004-05/0170.html > > Thanks in advance for your assistance, > Dave > > -- > Dave Leach > Agilent Technologies, Inc. I just noticed that the newsgroup search result you had was one of my
earlier postings on the issue before finding the cause and workaround. As I said, if you look in the windowsforms newsgroups you should find postings on the results of my investigations and the workaround. Show quote "Dave Leach" <babel@newsgroups.nospam> wrote in message news:D0BE86F8-8A55-468F-B1A8-0DEB187CDDB4@microsoft.com... >I am developing a Windows Forms based application using VS 2003 in C#. An > exception is being hit very rarely during acceptance testing. > > Is this a known defect? > Is there a workaround? > Is it corrected in .NET 2.0? > > Problem: Very intermittent Null Reference Exception deep in Windows code > after calling 'Forms.TabPageCollection.Remove' method > > Details: > - Always occurs with stack frames mentioning "ParkingWindow" on the > backtrace (see following). > - Has been seen originating with Controls.Clear() method as well. > - The same code path gets executed a great number of times without > problems. Only very rarely does an exception get thrown. Given the > difficulting in repeating the problem not much more is known about the > circumstances. > > Stack Backtrace: > Additional Info: System.NullReferenceException: Object reference not set > to > an instance of an object. > at System.Windows.Forms.WndProc.Invoke(IntPtr hWnd, Int32 msg, IntPtr > wParam, IntPtr lParam) > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > at System.Windows.Forms.Control.DefWndProc(Message& m) > at System.Windows.Forms.Control.WmUpdateUIState(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ContainerControl.WndProc(Message& m) > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > at System.Windows.Forms.Control.DefWndProc(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ContainerControl.WndProc(Message& m) > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > at System.Windows.Forms.Control.DefWndProc(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > at System.Windows.Forms.Control.DefWndProc(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, > Int32 msg, Int32 wParam, Int32 lParam) > at System.Windows.Forms.Control.SendMessage(Int32 msg, Int32 wparam, > Int32 lparam) > at System.Windows.Forms.Control.WmCreate(Message& m) > at System.Windows.Forms.Control.WndProc(Message& m) > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > IntPtr wparam, IntPtr lparam) > at System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 > x, > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, > HandleRef hInst, Object pvParam) > at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 > x, > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, > HandleRef hInst, Object pvParam) > at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) > at System.Windows.Forms.Control.CreateHandle() > at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) > at System.Windows.Forms.Control.CreateControl() > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > at System.Windows.Forms.Control.AssignParent(Control value) > at System.Windows.Forms.TabPage.AssignParent(Control value) > at System.Windows.Forms.ControlCollection.Remove(Control value) > at System.Windows.Forms.ControlCollection.Remove(Control value) > at System.Windows.Forms.TabPageCollection.Remove(TabPage value) > at <our application code> > > Possible reference found in Google search: > - Webpage "Derived combo box controls in forms - MessageBox.Show breaks > the control's message routing" indicates that derived ComboBox controls > might > be involved - that is possible in our situation. See > http://www.tech-archive.net/Archive/DotNet/microsoft.public.dotnet.languages.vb.controls/2004-05/0170.html > > Thanks in advance for your assistance, > Dave > > -- > Dave Leach > Agilent Technologies, Inc. Clive,
In one of your postings you said that you think this problem has been fixed in .NET 2.0. How did you determine this? Did Microsoft acknowledge the problem and state that it had been fixed? Was there a Knowledge Base article produced? Thanks for any information you can provide. Dave -- Show quoteDave Leach Agilent Technologies, Inc. "Clive Dixon" wrote: > I just noticed that the newsgroup search result you had was one of my > earlier postings on the issue before finding the cause and workaround. As I > said, if you look in the windowsforms newsgroups you should find postings on > the results of my investigations and the workaround. > > "Dave Leach" <babel@newsgroups.nospam> wrote in message > news:D0BE86F8-8A55-468F-B1A8-0DEB187CDDB4@microsoft.com... > >I am developing a Windows Forms based application using VS 2003 in C#. An > > exception is being hit very rarely during acceptance testing. > > > > Is this a known defect? > > Is there a workaround? > > Is it corrected in .NET 2.0? > > > > Problem: Very intermittent Null Reference Exception deep in Windows code > > after calling 'Forms.TabPageCollection.Remove' method > > > > Details: > > - Always occurs with stack frames mentioning "ParkingWindow" on the > > backtrace (see following). > > - Has been seen originating with Controls.Clear() method as well. > > - The same code path gets executed a great number of times without > > problems. Only very rarely does an exception get thrown. Given the > > difficulting in repeating the problem not much more is known about the > > circumstances. > > > > Stack Backtrace: > > Additional Info: System.NullReferenceException: Object reference not set > > to > > an instance of an object. > > at System.Windows.Forms.WndProc.Invoke(IntPtr hWnd, Int32 msg, IntPtr > > wParam, IntPtr lParam) > > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > > at System.Windows.Forms.Control.DefWndProc(Message& m) > > at System.Windows.Forms.Control.WmUpdateUIState(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ContainerControl.WndProc(Message& m) > > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > > at System.Windows.Forms.Control.DefWndProc(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ContainerControl.WndProc(Message& m) > > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > > at System.Windows.Forms.Control.DefWndProc(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > > at System.Windows.Forms.Control.DefWndProc(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, > > Int32 msg, Int32 wParam, Int32 lParam) > > at System.Windows.Forms.Control.SendMessage(Int32 msg, Int32 wparam, > > Int32 lparam) > > at System.Windows.Forms.Control.WmCreate(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 > > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 > > x, > > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, > > HandleRef hInst, Object pvParam) > > at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 > > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 > > x, > > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, > > HandleRef hInst, Object pvParam) > > at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) > > at System.Windows.Forms.Control.CreateHandle() > > at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) > > at System.Windows.Forms.Control.CreateControl() > > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.AssignParent(Control value) > > at System.Windows.Forms.TabPage.AssignParent(Control value) > > at System.Windows.Forms.ControlCollection.Remove(Control value) > > at System.Windows.Forms.ControlCollection.Remove(Control value) > > at System.Windows.Forms.TabPageCollection.Remove(TabPage value) > > at <our application code> > > > > Possible reference found in Google search: > > - Webpage "Derived combo box controls in forms - MessageBox.Show breaks > > the control's message routing" indicates that derived ComboBox controls > > might > > be involved - that is possible in our situation. See > > http://www.tech-archive.net/Archive/DotNet/microsoft.public.dotnet.languages.vb.controls/2004-05/0170.html > > > > Thanks in advance for your assistance, > > Dave > > > > -- > > Dave Leach > > Agilent Technologies, Inc. > > > Clive,
I forgot to mention that I searched for your posting and could not find it. However, I did find postings to other sites by using Google. Has it aged off the MSDN newsgroup system? Maybe there is another search method I am unaware of. Can you still find the posting and if so how? Thanks, Dave -- Show quoteDave Leach Agilent Technologies, Inc. "Clive Dixon" wrote: > I just noticed that the newsgroup search result you had was one of my > earlier postings on the issue before finding the cause and workaround. As I > said, if you look in the windowsforms newsgroups you should find postings on > the results of my investigations and the workaround. > > "Dave Leach" <babel@newsgroups.nospam> wrote in message > news:D0BE86F8-8A55-468F-B1A8-0DEB187CDDB4@microsoft.com... > >I am developing a Windows Forms based application using VS 2003 in C#. An > > exception is being hit very rarely during acceptance testing. > > > > Is this a known defect? > > Is there a workaround? > > Is it corrected in .NET 2.0? > > > > Problem: Very intermittent Null Reference Exception deep in Windows code > > after calling 'Forms.TabPageCollection.Remove' method > > > > Details: > > - Always occurs with stack frames mentioning "ParkingWindow" on the > > backtrace (see following). > > - Has been seen originating with Controls.Clear() method as well. > > - The same code path gets executed a great number of times without > > problems. Only very rarely does an exception get thrown. Given the > > difficulting in repeating the problem not much more is known about the > > circumstances. > > > > Stack Backtrace: > > Additional Info: System.NullReferenceException: Object reference not set > > to > > an instance of an object. > > at System.Windows.Forms.WndProc.Invoke(IntPtr hWnd, Int32 msg, IntPtr > > wParam, IntPtr lParam) > > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > > at System.Windows.Forms.Control.DefWndProc(Message& m) > > at System.Windows.Forms.Control.WmUpdateUIState(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ContainerControl.WndProc(Message& m) > > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > > at System.Windows.Forms.Control.DefWndProc(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ContainerControl.WndProc(Message& m) > > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > > at System.Windows.Forms.Control.DefWndProc(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr > > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) > > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) > > at System.Windows.Forms.Control.DefWndProc(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, > > Int32 msg, Int32 wParam, Int32 lParam) > > at System.Windows.Forms.Control.SendMessage(Int32 msg, Int32 wparam, > > Int32 lparam) > > at System.Windows.Forms.Control.WmCreate(Message& m) > > at System.Windows.Forms.Control.WndProc(Message& m) > > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) > > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) > > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) > > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, > > IntPtr wparam, IntPtr lparam) > > at System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 > > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 > > x, > > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, > > HandleRef hInst, Object pvParam) > > at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 > > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 > > x, > > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, > > HandleRef hInst, Object pvParam) > > at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) > > at System.Windows.Forms.Control.CreateHandle() > > at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) > > at System.Windows.Forms.Control.CreateControl() > > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs e) > > at System.Windows.Forms.Control.AssignParent(Control value) > > at System.Windows.Forms.TabPage.AssignParent(Control value) > > at System.Windows.Forms.ControlCollection.Remove(Control value) > > at System.Windows.Forms.ControlCollection.Remove(Control value) > > at System.Windows.Forms.TabPageCollection.Remove(TabPage value) > > at <our application code> > > > > Possible reference found in Google search: > > - Webpage "Derived combo box controls in forms - MessageBox.Show breaks > > the control's message routing" indicates that derived ComboBox controls > > might > > be involved - that is possible in our situation. See > > http://www.tech-archive.net/Archive/DotNet/microsoft.public.dotnet.languages.vb.controls/2004-05/0170.html > > > > Thanks in advance for your assistance, > > Dave > > > > -- > > Dave Leach > > Agilent Technologies, Inc. > > > Dave,
Sorry about delayed response through being a bit busy the last few days to read newsgroups. From memory (this is over a couple of years ago now at a different company) I think determined that it was fixed in .NET 2.0 simply by running the problematic software on a machine with only .NET 2.0 (it might have been a beta) installed. There was no official acknowledgement by MS that there was a bug in 1.1 or that it was fixed in 2.0, to my knowledge. I did post in this newsgroup thread: http://groups.google.co.uk/group/microsoft.public.dotnet.framework.windowsforms/browse_thread/thread/40fee9009f646f3c/f9b737171aca1a48?lnk=st&q=&rnum=3&hl=en#f9b737171aca1a48 and MS's Ying-Shen Yu in this thread said he would look into it. I didn't do any follow up any further with MS as we had a workaround for our problem and it was apparently fixed with 2.0. Show quote "Dave Leach" <babel@newsgroups.nospam> wrote in message news:347FE0AF-8165-4186-8E99-4FEAEA8EB159@microsoft.com... > Clive, > > I forgot to mention that I searched for your posting and could not find > it. > However, I did find postings to other sites by using Google. > > Has it aged off the MSDN newsgroup system? Maybe there is another search > method I am unaware of. Can you still find the posting and if so how? > > Thanks, > Dave > > -- > Dave Leach > Agilent Technologies, Inc. > > > "Clive Dixon" wrote: > >> I just noticed that the newsgroup search result you had was one of my >> earlier postings on the issue before finding the cause and workaround. As >> I >> said, if you look in the windowsforms newsgroups you should find postings >> on >> the results of my investigations and the workaround. >> >> "Dave Leach" <babel@newsgroups.nospam> wrote in message >> news:D0BE86F8-8A55-468F-B1A8-0DEB187CDDB4@microsoft.com... >> >I am developing a Windows Forms based application using VS 2003 in C#. >> >An >> > exception is being hit very rarely during acceptance testing. >> > >> > Is this a known defect? >> > Is there a workaround? >> > Is it corrected in .NET 2.0? >> > >> > Problem: Very intermittent Null Reference Exception deep in Windows >> > code >> > after calling 'Forms.TabPageCollection.Remove' method >> > >> > Details: >> > - Always occurs with stack frames mentioning "ParkingWindow" on the >> > backtrace (see following). >> > - Has been seen originating with Controls.Clear() method as well. >> > - The same code path gets executed a great number of times without >> > problems. Only very rarely does an exception get thrown. Given the >> > difficulting in repeating the problem not much more is known about the >> > circumstances. >> > >> > Stack Backtrace: >> > Additional Info: System.NullReferenceException: Object reference not >> > set >> > to >> > an instance of an object. >> > at System.Windows.Forms.WndProc.Invoke(IntPtr hWnd, Int32 msg, IntPtr >> > wParam, IntPtr lParam) >> > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr >> > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) >> > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) >> > at System.Windows.Forms.Control.DefWndProc(Message& m) >> > at System.Windows.Forms.Control.WmUpdateUIState(Message& m) >> > at System.Windows.Forms.Control.WndProc(Message& m) >> > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) >> > at System.Windows.Forms.ContainerControl.WndProc(Message& m) >> > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) >> > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, >> > IntPtr wparam, IntPtr lparam) >> > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr >> > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) >> > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) >> > at System.Windows.Forms.Control.DefWndProc(Message& m) >> > at System.Windows.Forms.Control.WndProc(Message& m) >> > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) >> > at System.Windows.Forms.ContainerControl.WndProc(Message& m) >> > at System.Windows.Forms.ParkingWindow.WndProc(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) >> > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, >> > IntPtr wparam, IntPtr lparam) >> > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr >> > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) >> > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) >> > at System.Windows.Forms.Control.DefWndProc(Message& m) >> > at System.Windows.Forms.Control.WndProc(Message& m) >> > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) >> > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, >> > IntPtr wparam, IntPtr lparam) >> > at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr >> > wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) >> > at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) >> > at System.Windows.Forms.Control.DefWndProc(Message& m) >> > at System.Windows.Forms.Control.WndProc(Message& m) >> > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) >> > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, >> > IntPtr wparam, IntPtr lparam) >> > at System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef >> > hWnd, >> > Int32 msg, Int32 wParam, Int32 lParam) >> > at System.Windows.Forms.Control.SendMessage(Int32 msg, Int32 wparam, >> > Int32 lparam) >> > at System.Windows.Forms.Control.WmCreate(Message& m) >> > at System.Windows.Forms.Control.WndProc(Message& m) >> > at System.Windows.Forms.ScrollableControl.WndProc(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) >> > at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) >> > at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, >> > IntPtr wparam, IntPtr lparam) >> > at System.Windows.Forms.UnsafeNativeMethods.IntCreateWindowEx(Int32 >> > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, >> > Int32 >> > x, >> > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef >> > hMenu, >> > HandleRef hInst, Object pvParam) >> > at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 >> > dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, >> > Int32 >> > x, >> > Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef >> > hMenu, >> > HandleRef hInst, Object pvParam) >> > at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp) >> > at System.Windows.Forms.Control.CreateHandle() >> > at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible) >> > at System.Windows.Forms.Control.CreateControl() >> > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) >> > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs >> > e) >> > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) >> > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) >> > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs >> > e) >> > at System.Windows.Forms.Control.OnParentVisibleChanged(EventArgs e) >> > at System.Windows.Forms.Control.OnVisibleChanged(EventArgs e) >> > at System.Windows.Forms.ScrollableControl.OnVisibleChanged(EventArgs >> > e) >> > at System.Windows.Forms.Control.AssignParent(Control value) >> > at System.Windows.Forms.TabPage.AssignParent(Control value) >> > at System.Windows.Forms.ControlCollection.Remove(Control value) >> > at System.Windows.Forms.ControlCollection.Remove(Control value) >> > at System.Windows.Forms.TabPageCollection.Remove(TabPage value) >> > at <our application code> >> > >> > Possible reference found in Google search: >> > - Webpage "Derived combo box controls in forms - MessageBox.Show >> > breaks >> > the control's message routing" indicates that derived ComboBox controls >> > might >> > be involved - that is possible in our situation. See >> > http://www.tech-archive.net/Archive/DotNet/microsoft.public.dotnet.languages.vb.controls/2004-05/0170.html >> > >> > Thanks in advance for your assistance, >> > Dave >> > >> > -- >> > Dave Leach >> > Agilent Technologies, Inc. >> >> >>  |
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