When does Windows Error Reporting create a dump file? Is it configurable? Has this changed in Windows 7?

Question

I'm relying on Windows Error Reporting to create full user-mode dumps for a large, multi-threaded application. I know that when I started using it (early 2012) these dumps contained all application memory, and full stacks for all threads that were accurate for the time the application crashed (threw the unhandled exception, etc). But at at some unknown point in the last year, crash dumps created by WER have changed. They still contain all memory, but only show one thread, and the stack appears to be from after the process is already shutting down:

    ntdll.dll!_LdrpCallInitRoutine@16()  + 0x14 bytes   
    ntdll.dll!_LdrShutdownProcess@0()  + 0x141 bytes    
    ntdll.dll!_RtlExitUserProcess@4()  + 0x74 bytes 
    kernel32.dll!_UnhandledExceptionFilter@4()  + 0x18928 bytes 

This is an unmanaged (unmanagable?) 32-bit C++ application compiled with VS2010 SP1, running on 64-bit Win7 SP1 (and kept updated). Does anyone know of any Windows updates that have changed WER behavior in the last year? Is there something configurable other than 'HKLM\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps\AppName.exe'?

Also, killing the application by calling 'RaiseFailFastException' still results in a good dump with valid stacks for all threads.

Answer 1

Aha! A third-party library was calling SetUnhandledExceptionFilter, which prevented Windows Error Reporting from getting the original exception. Their handler did some internal cleanup, then called abort, at which point WER was finally able to create a dump.

For anyone encountering this sort of problem, I recommend checking that the installed handlers (the return values of SetUnhandledExceptionFilter, set_terminate, etc) are what you expect (null if you're relying on WER, or your own handlers or CrashRpt).

Answer 2

It is better to make your application self-dump-writer when it crashes. You just need to call SetUnhandledExceptionFilter function, specify the call back. In the call back, use MiniDumpWriteDump function with MiniDumpWithFullMemory dump type.

Your exception filter will be called whenever unhandled (by your code) exception occurs. In the call back, it will be better to enumerate and suspend all other threads of your process.

You may also need to install a hook for SetUnhandledExceptionFilter itself! Why? Well, CRT would always disable any installed exception filter, and by the hooked function, you may avoid that.