Exceptions silently caught by Windows, how to handle manually?


We're having problems with Windows silently eating exceptions and allowing the application to continue running, when the exception is thrown inside the message pump. For example, we created a test MFC MDI application, and overrode OnDraw:

void CTestView::OnDraw(CDC* /*pDC*/)
    *(int*)0 = 0; // Crash

    CTestDoc* pDoc = GetDocument();
    if (!pDoc)

    // TODO: add draw code for native data here

You would expect a nasty error message when running the application, but you actually get nothing at all. The program appears to be running perfectly well, but if you check the output window you will see:

First-chance exception at 0x13929384 in Test.exe: 0xC0000005: Access violation writing location 0x00000000.
First-chance exception at 0x77c6ee42 in Test.exe: 0xC0150010: The activation context being deactivated is not active for the current thread of execution.

I know why I'm receiving the application context exception, but why is it being handled silently? It means our applications could be suffering serious problems when in use, but we'll never know about it, because our users will never report any problems.

asked on Stack Overflow Apr 12, 2010 by Mark Ingram • edited Apr 12, 2010 by Johan

7 Answers


If you're running on an x64 OS you may have been bitten by this:


Or (less likely in this case), it may be this: http://blogs.msdn.com/b/oldnewthing/archive/2011/01/20/10117963.aspx

answered on Stack Overflow Feb 2, 2011 by Simon Hofverberg • edited Jan 16, 2020 by mirh

After browsing similar questions I stumbled across this answer: OpenGL suppresses exceptions in MFC dialog-based application

"Ok, I found out some more information about this. In my case it's windows 7 that installs KiUserCallbackExceptionHandler as exception handler, before calling my WndProc and giving me execution control. This is done by ntdll!KiUserCallbackDispatcher. I suspect that this is a security measure taken by Microsoft to prevent hacking into SEH.

The solution is to wrap your wndproc (or hookproc) with a try/except frame."

I've filed a bug report with Microsoft, you can see their response here:

From Microsoft:

Thanks for the report. I've found out that this is a Windows issue, and there is a hot fix available. Please see http://support.microsoft.com/kb/976038 for a fix that you can install if you wish.

answered on Stack Overflow Apr 12, 2010 by Mark Ingram • edited May 23, 2017 by Community

functions that may be of interest:


PS, be aware that SetUnhandledExceptionFilter() can be overriden by other dlls loaded into your .exe. eg, flash and nvidia direct3d do this. I use api hooking to cure this.

answered on Stack Overflow Apr 12, 2010 by SteelBytes

I experienced this same issue, and found it was a result of this Microsoft bug: http://connect.microsoft.com/VisualStudio/feedback/details/550944/hardware-exceptions-on-x64-machines-are-silently-caught-in-wndproc-messages

There’s a fix available from Microsoft, though deploying it is somewhat challenging if you have multiple target platforms:


Here's an article on the subject describing the behavior:


The issue is basically that Hardware exceptions in 32-bit programs are silently caught in the WndProc routine on 64-bit OSs, unless you send commands telling it not to. Microsoft has a hotfix for the issue that is required if you're running Vista SP2, but isn't required with Windows 7 SP1 (not sure about Win7 without the SP).

Even WITH the hotfix, you need to enable the correct behavior by setting a registry key or making some calls to the kernel to tell it your process expects hardware exceptions to crash when encountered during WndProc.

According to the PaulBetts link above, this was done for backwards compatibility with Windows Server 2003.

If you program is a 64-bit program, this issue goes away.

answered on Stack Overflow Jan 10, 2012 by Brian

ANSWER IN HINDSIGHT for anyone who stumbles upon this later.

This was caused by a known issue in Windows http://support.microsoft.com/kb/976038 - make sure you're up to date, install the hotpatch if you need to, and mark your application as Windows 7 compatible. http://msdn.microsoft.com/en-us/library/dd371711%28v=vs.85%29.aspx

I've seen this with exception codes c015000f and c0150010.

answered on Stack Overflow Aug 5, 2011 by David

You can force Windows to not ignore the exceptions with this code snippet (from Microsoft's Exceptions that are thrown from an application that runs in a 64-bit version of Windows are ignored) that you will put in your process code:

// my SDK is v6.0A and the two APIs are not available in the .h files, so I need to get them at runtime
HINSTANCE h = ::LoadLibrary(L"kernel32.dll");
if ( h ) {
   GETPROCESSUSERMODEEXCEPTIONPOLICY GetProcessUserModeExceptionPolicy = reinterpret_cast< GETPROCESSUSERMODEEXCEPTIONPOLICY >( ::GetProcAddress(h, "GetProcessUserModeExceptionPolicy") );
   SETPROCESSUSERMODEEXCEPTIONPOLICY SetProcessUserModeExceptionPolicy = reinterpret_cast< SETPROCESSUSERMODEEXCEPTIONPOLICY >( ::GetProcAddress(h, "SetProcessUserModeExceptionPolicy") );
   if ( GetProcessUserModeExceptionPolicy == 0 || SetProcessUserModeExceptionPolicy == 0 ) {
   DWORD dwFlags;
   if (GetProcessUserModeExceptionPolicy(&dwFlags)) {
      SetProcessUserModeExceptionPolicy(dwFlags & ~PROCESS_CALLBACK_FILTER_ENABLED); 

It may be you have to add also an unhandled exception filter: the filter acts like a "top level exception handler" that is like a topmost catch block. For extracting a programmer-friendly string from _EXCEPTION_POINTERS you can see Is there a function to convert EXCEPTION_POINTERS struct to a string?

LONG WINAPI my_filter(_In_  struct _EXCEPTION_POINTERS *ExceptionInfo)
   ::OutputDebugStringA("an exception occured!");

You add the filter with:


and you have to do it in every threads of your process: while the previous snippet is per-process, the filter is per-thread.

answered on Stack Overflow Nov 28, 2012 by Alessandro Jacopson • edited May 23, 2017 by Community

Your output looks like you're using Visual Studio...
If not forget about my answer.
You can specify which exceptions will be thrown normally, meaning that Visual Studio catches them and your progam stops where the access violation occurred. Do this in the Debug/Exceptions... menu. If you are not sure what to enable, just enable them all...

answered on Stack Overflow Apr 12, 2010 by Simon Linder

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