Such problem often occures because of incorrect signature of message handle functions, that included into MFC message map for your CWnd based class.
We should very carefully check signatures such functions in comparision with expected one by MFC library. For example, if you put follow handler into message map

ON_MESSAGE(WM_SOME_USER_MESSAGE, OnMyMessage)

and define OnMyMessage as:

void CMyWnd::OnMyMessage()
{
//do something
}

this code will be compiled without errors. DEBUG build can work without any problems, but RELEASE will crash besause ON_MESSAGE macro expect follow
signature:

LRESULT CMyWnd::OnMyMessage(WPARAM /*wParam*/, LPARAM /*lParam*/)

DEBUG build works because stack processing has differences for debug and release builds.

so, the solution is simple:

Solution 1:  modify the  message handle functions with the following style and it will be ok.

void CMyWnd::OnMyMessage(WPARAM wParam, LPARAM lParam)

Solution 2:  don’t modify the message handle functios, and change the ON_MESSAGE macro to ON_MESSAGE_VOID.

ON_MESSAGE_VOID(WM_SOME_USER_MESSAGE, OnMyMessage)


This macro is in AfxPriv.h, but is largely undocumented.

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Display the LastError’s value

When we want to get the LastError message, we often using the following code.

LPVOID lpMsgBuf;
FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
NULL,
GetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
(LPTSTR) &lpMsgBuf,
0,
NULL
);
// Process any inserts in lpMsgBuf.
// …
// Display the string.
MessageBox( NULL, (LPCTSTR)lpMsgBuf, “Error”, MB_OK | MB_ICONINFORMATION );
// Free the buffer.
LocalFree( lpMsgBuf );


But now VisualSudio 6.0 has provied a virtual Pseudoregister called @ERR
we can simply input the expression in the watch window and we will get the LastError message.@ERR,hrHere is supported pseudoregisters list:[1]


@ERR
;Last error value,the same value returned by the GetLastError() API function

@TIB
;Thread information block for the current thread

@CLK
;Undocumented clock register; usable only in the Watch window

@EAX, @EBX, @ECX, @EDX, @ESI, @EDI, @EIP, @ESP, @EBP, @EFL
;Intel CPU registers

@CS, @DS, @ES, @SS, @FS, @GS
;Intel CPU segment registers

@ST0, @ST1, @ST2, @ST3, @ST4, @ST5, @ST6, @ST7
;Intel CPU floating-point registers

Acknowledge:

[1]An introduction to debugging in MSVC++ using Pseudoregisters

[2]Microsoft Visual C++ Tips and Tricks

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