CODEWITHSUNDEEP
c++visual-studiodebuggingexceptionvisual-c++
Francis Straccia
Francis Straccia

Reputation: 916

Visual Studio breaks on breakpoint on start randomly while debugging

While starting a Visual C++ ATL/WTL application in the Visual Studio 2015 debugger, sometimes as soon as debug is launched Visual Studio breaks on a non existing breakpoint stating, on the classic Exception window:

"Appname.exe has hit a breakpoint"
Break | Cancel | Continue

No other information is given about the exception. When I break into, sometimes it says

No source code available

while some other times is

Frame not in module

Either way, when I click on "Show disassembly", this is what I see:

...
77038EFD  ?? ?? 
77038EFE  ?? ?? 
77038EFF  dec         dword ptr [ecx-76FBDBBCh]  
77038F05  pop         esp  
77038F06  and         al,8  
77038F08  jmp         __RtlUserThreadStart@8 (77025D93h)  
77038F0D  lea         ecx,[ecx]  
_KiFastSystemCall@0:
77038F10  mov         edx,esp  
77038F12  sysenter  
77038F14  lea         esp,[esp]  
77038F1B  jmp         _KiFastSystemCallRet@0 (77038F20h)  
...

It breaks exactly on 

77038EFF  dec         dword ptr [ecx-76FBDBBCh]

If I step over, step into or continue, the application starts and works normally.

The application is compiled with no optimization and with all debug flags on. As I stated at the beginning, it happens only sometimes, let's say 1/3 of the times. The application is always the same between launches.

If I start the very same application outside VS, it works normally.

Any ideas on what could cause this strange behaviour?

Upvotes: 3

Views: 1275

Answers (1)

Francis Straccia
Francis Straccia

Reputation: 916

As it turns out, it seems that this strange behaviour is triggered by enabling a conditional breakpoint.

Even if the breakpoint is disabled, the behaviour continues to remain until VS is restarted.

Upvotes: 1

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