DbgHelp fails in a Windows service

Question

I am trying to download debugging symbols from a .NET Windows service. The service calls a helper dll that does the actual calls into dbghelp.dll. I've found that the call to SymGetTypeFromNameW fails but GetLastError returns 0.  If I run the exact
same code but in a Windows form application it works exactly as it should.  This is not a versioning issue because I load dbghelp with LoadLibrary with the exact path of the version I want to use and have verified through the debugger that it has actually
loaded the correct version. 
Here is the snippet of code that fails with a service but works with a form app.
 sz = sizeof(SYMBOL_INFOW) + MAX_SYM_NAME + 1;
 siw = (PSYMBOL_INFOW)malloc(sz);
 ZeroMemory(siw, sz);
 siw->SizeOfStruct = sizeof(SYMBOL_INFOW);
 siw->MaxNameLen   = MAX_SYM_NAME + 1;
 bRet = SymGetTypeFromNameW(proc, mb, sn, siw);
 if (!bRet) {
  gle = GetLastError();
  DebugBreak();
  free(siw);
  return gle;
I have not yet stepped through the call to see where it fails but I'm wondering if anyone else has had this issue and if so knows a way to solve it.  Thanks.

Answer 1

Hi DevOps26,
Like this document:
https://msdn.microsoft.com/en-us/library/windows/desktop/ms679309(v=vs.85).aspx
As my understanding, the DbgHelp would be related to the windows debugging, I help you move this case to the
WinDbg forum for dedicated support. Thanks for your understanding.
Best Regards,
Jack
We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
Click
HERE to participate the survey.