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Asked: 2026-05-15T03:27:28+00:00

I have written a COM object that in turn uses a thrid party ActiveX

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I have written a COM object that in turn uses a thrid party ActiveX control. In my FinalConstruct() for my COM object, I instantiate the ActiveX control with the follow code:

  HRESULT hRes;
  LPCLASSFACTORY2 pClassFactory;
  hRes = CoInitializeEx(NULL,COINIT_APARTMENTTHREADED);
  bool bTest = SUCCEEDED(hRes);
  if (!bTest)
   return E_FAIL;
  if (SUCCEEDED(CoGetClassObject(__uuidof(SerialPortSniffer), CLSCTX_INPROC_SERVER, NULL,
   IID_IClassFactory2, (LPVOID *)(&pClassFactory))))
  {  ... more set up code

When I step over the line if (SUCCEEDED(CoGetClassObject(__uuidof(SerialPortSniffer), …,
I get 20+ lines in the Output window stating:

First-chance exception at 0x0523f82e
in SillyComDriver.exe: 0xC0000005:
Access violation writing location
0x00000000.

I also get the lines:

First-chance exception at 0x051e3f3d
in SillyComDriver.exe: 0xC0000096:
Privileged instruction. First-chance
exception at 0x100ab9e6 in
SillyComDriver.exe: 0xC000001D:
Illegal Instruction.

Notice these are first-chance exceptions. The program runs as expected I can access the third party methods/properties. Still, I’m left wondering why they are occurring. Perhaps my way of instantiating the ActiveX control (for which I want use of it’s methods/properties and not it’s GUI stuff) is incorrect? Besides the code I’m showing, I also put the line

#import "spsax.dll" no_namespace

in the stdafx.h
That’s all the code necessary for my simple demo project. I noticed this problem because I had (inadvertently) set the “break on exceptions” options in my “real” project and it was breaking on this line. Once I removed it, it also works.

If you’re read this far thank you, and perhaps I can ask one other minor question. In my demo project, if I right click on SerialPortSniffer and “go to definition”, it takes me to the file C:….\AppData\Local\Temp\spsax.tlh. Can someone explain that? Finally, in my “real” project, right clicking on SerialPortSniffer and going to difinition leads to “The symbol ‘SerialPortSniffer’ is not defined”. It doesn’t seem to affect the program though. Is there some setting I’ve messed up?

By the way, all my code is written w/ VS2008.

Thanks,
Dave

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1 Answer

  1. Editorial Team

    It’s usually nothing to worry about.

    When an exception is thrown, the debugger is notified and depending on the debugger configuration, it may stop the application or let the application resume normally. This is a "first-chance" exception. If the application resumes, then it may catch the exception, and do whatever is necessary in the exceptional case.

    If the application does not handle the exception, it becomes a "second-chance" exception and the debugger is notified again. The debugger is usually configured to stop the application at this point to let you see what went wrong.

    So if you get a first-chance exception and not receive a second-chance exception later, it’s usually means that nothing is wrong, and the application is handling exceptions in a "graceful" matter.

    (Also see Link)

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