AccessViolationException: Attempted to read or write protected memory...

[Marc Bartsch]

Hi,

My C# app throws the following exception:

System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

From what I read so far I found that the problem can be connected to P/Invoke and that the places at which this exception is thrown might not reflect the actual problem. In my case, the exception is thrown, when I try to minimise my main window to the system tray and to hide the window from the taskbar:

public void Minimize()
{
this.WindowState = FormWindowState.Minimized;
this.ShowInTaskbar = false; // Exception!
this.Visible = false;
this.exit = true;
}

Here is more detail:

1. I removed all code that deals with P/Invoke, all DLLImports and so on to make sure I am using only fully managed code.

2. I turned off any virus scanner. This could be one possible source of the problem.

3. My configuration is: VS 2005 (SP1 and Vista update), C#, .NET 2, Vista Business.

4. Even though my app contains code to make a web service call, such code will not be called in the scenario that causes the exception. I read that remoting can be a source of the problem.

5. I can reproduce the problem on my machine. Below is a Stack Trace and a Call Stack output. It starts in an OnClosing event that I connect to and then follows a call to the Minimize method before leaping into .NET with ShowInTaskbar (the idea is to cancel the closing of the form in this scenario, to minimize it and to show a tray icon). What I find odd, is the fact that the TreeView Control is involved in the .NET code and that a TreeNode is set in this stack trace. An implementation of TreeView.afterSelect shows that this event will indeed be fired while ShowInTaskbar has been called. I mention this because in the scenario, in which the exception is thrown, I have to expand a few tree node and to send the app to the system tray one or two times until the exception is thrown.

Any idea what could cause the exception?

Thanks and best wishes,

Marc.

Stack Trace from Exception dialog:

" at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam)\r\n at System.Windows.Forms.NativeWindow.DefWndProc(Message& m)"

Call Stack:

System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DefWndProc(ref System.Windows.Forms.Message m = {msg=0x110b hwnd=0x1110704 wparam=0x9
lparam=0x3fb6cf0 result=0x0}) + 0x94 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.DefWndProc(ref System.Windows.Forms.Message m) + 0xc bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.WndProc(ref System.Windows.Forms.Message m) + 0x90b bytes
System.Windows.Forms.dll!System.Windows.Forms.TreeView.WndProc(ref System.Windows.Forms.Message m) + 0xedf bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMessage(ref System.Windows.Forms.Message m) + 0xd bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndProc(ref System.Windows.Forms.Message m) + 0xd6 bytes
System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DebuggableCallback(System.IntPtr hWnd, int msg = 4363, System.IntPtr wparam, System.IntPtr lparam) + 0x75 bytes
[Native to Managed Transition]
[Managed to Native Transition]
System.Windows.Forms.dll!System.Windows.Forms.Control.SendMessage(int msg, int wparam, System.IntPtr lparam) + 0x44 bytes
System.Windows.Forms.dll!System.Windows.Forms.TreeView.SelectedNode.set(System.Windows.Forms.TreeNode value) + 0x74 bytes
System.Windows.Forms.dll!System.Windows.Forms.TreeView.OnHandleCreated(System.EventArgs e) + 0x331 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.WmCreate(ref System.Windows.Forms.Message m) + 0x40 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.WndProc(ref System.Windows.Forms.Message m) + 0x447 bytes
System.Windows.Forms.dll!System.Windows.Forms.TreeView.WndProc(ref System.Windows.Forms.Message m) + 0xedf bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMessage(ref System.Windows.Forms.Message m) + 0xd bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndProc(ref System.Windows.Forms.Message m) + 0xd6 bytes
System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DebuggableCallback(System.IntPtr hWnd, int msg = 1, System.IntPtr wparam, System.IntPtr lparam) + 0x75 bytes
[Native to Managed Transition]
[Managed to Native Transition]
System.Windows.Forms.dll!System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(int dwExStyle, string lpszClassName, string lpszWindowName, int style, int
x, int y, int width, int height,
System.Runtime.InteropServices.HandleRef hWndParent,
System.Runtime.InteropServices.HandleRef hMenu,
System.Runtime.InteropServices.HandleRef hInst, object pvParam) + 0x45 bytes
System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.CreateHandle(System.Windows.Forms.CreateParams
cp) + 0x241 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.CreateHandle() + 0x16a bytes
System.Windows.Forms.dll!System.Windows.Forms.TreeView.CreateHandle() + 0x6c bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.RecreateHandleCore() + 0x11b bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.OnParentHandleRecreated() + 0xe4 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.RecreateHandleCore() + 0x207 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.OnParentHandleRecreated() + 0xe4 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.RecreateHandleCore() + 0x207 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.OnParentHandleRecreated() + 0xe4 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.RecreateHandleCore() + 0x207 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.OnParentHandleRecreated() + 0xe4 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.RecreateHandleCore() + 0x207 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.OnParentHandleRecreated() + 0xe4 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.RecreateHandleCore() + 0x207 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.OnParentHandleRecreated() + 0xe4 bytes
System.Windows.Forms.dll!System.Windows.Forms.Control.RecreateHandleCore() + 0x207 bytes
System.Windows.Forms.dll!System.Windows.Forms.Form.RecreateHandleCore() + 0x25e bytes
System.Windows.Forms.dll!System.Windows.Forms.Form.ShowInTaskbar.set(bool value) + 0xdc bytes

backup.exe!Adonec.Backup.MainForm.Minimize() Line 392 + 0x9 bytes C#

backup.exe!Adonec.Backup.MainForm.OnClosing(System.ComponentModel.CancelEventArgs e = {System.Windows.Forms.FormClosingEventArgs}) Line 367 + 0x7 bytes C#

 

[Marc Bartsch]

Hi,

My C# app throws the following exception:

System.AccessViolationException: Attempted to read or write protected
memory. This is often an indication that other memory is corrupt.

From what I read so far I found that the problem can be connected to
P/Invoke and that the places at which this exception is thrown might not
reflect the actual problem. In my case, the exception is thrown, when I
try to minimise my main window to the system tray and to hide the window
from the taskbar:

After further tests, I found out that disabling Visual Styles in my application seems to get rid of the problem:

[STAThread]
static void Main(string[] args)
{
//Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
MainForm mf = new MainForm();

Application.Run(mf);
}

Without visual styles I cannot reproduce the exception anymore. With visual styles, it is reproducable in Debug and Release configuration. This may not be the actual problem and disabling visual styles may only mask the real problem, but this exception seems very hard to track down.

Does anyone know whether visual styles could have something to do with an AccessViolationException?

Best wishes,

Marc.

 

[ktrvnbq02]

Without visual styles I cannot reproduce the exception anymore. With visual styles, it is reproducable in Debug and Release configuration. This may not be the actual problem and disabling visual styles may only mask the real problem, but this exception seems very hard to track down.

Does anyone know whether visual styles could have something to do with an AccessViolationException?

Some possibilities I can think of that might be triggering such
behaviour:

1. A hardware problem on your machine, such as a RAM fault that just
happens to interfere with the code that manages Visual Styles in this
circumstance. I could be worth running WinDiag to see if it shows any
faults: http://oca.microsoft.com/en/windiag.asp

2. A bug in the video driver being triggered by the codepaths in your
application when Visual Styles are in use. It might be worth checking
for an updated version of the video driver.

3. Another application (e.g. some kind of window management app) that
runs on your machine that inserts code into other processes and
happens to cause a crash.


Regards,

Matt

 

[Marc Bartsch]

Hi Matt,

Some possibilities I can think of that might be triggering such
behaviour:

1. A hardware problem on your machine, such as a RAM fault that just
happens to interfere with the code that manages Visual Styles in this
circumstance. I could be worth running WinDiag to see if it shows any
faults: http://oca.microsoft.com/en/windiag.asp

I tried WinDiag, but everything was fine.

2. A bug in the video driver being triggered by the codepaths in your
application when Visual Styles are in use. It might be worth checking
for an updated version of the video driver.

That might be it, but there is unfortunately no updated version of my video driver.

3. Another application (e.g. some kind of window management app) that
runs on your machine that inserts code into other processes and
happens to cause a crash.

I stopped all applications which might interfere, but the problem persists.

I tried my program on a different machine and everything worked fine. It seems that the video driver might be a good guess as to where the problem comes from.

Thanks,

Marc.