Article ID: 189383
Article Last Modified on 11/21/2006
APPLIES TO
- Microsoft Foundation Class Library 4.2, when used with:
- Microsoft Visual C++ 5.0 Enterprise Edition
- Microsoft Visual C++ 5.0 Professional Edition
This article was previously published under Q189383
SYMPTOMS
An ASSERT can occur when a non-MFC application tries to load, free, and
again load an MFC Regular DLL. The assert occurs in the Auxdata.cpp file as
a result of a failed call to GetSysColorBrush. The specific code is:
hbrBtnFace = ::GetSysColorBrush(COLOR_BTNFACE);
ASSERT(hbrBtnFace != NULL);
The ASSERT statement is at line 139 of Auxdata.cpp in MFC version 4.2 that
ships with Visual C++ 5.0.
CAUSE
User32.dll leaks resources, which causes ::GetSysColorBrush to fail.
RESOLUTION
If a non-MFC application intends to load and free a Regular DLL, make sure
that User32.dll is not also being unloaded when FreeLibrary is used to free
the DLL. To do so, you can call LoadLibrary to load User32.dll once in the
application, before the application loads and frees the Regular DLL.
STATUS
Microsoft is researching this problem and will post new information here in
the Microsoft Knowledge Base as it becomes available.
MORE INFORMATION
In its initialization process, MFC loads User32.dll. The ASSERT occurs when
the Regular DLL is the only module in an application that uses User32.dll
(including the application). If this application loads, frees, and again
loads this DLL, the ASSERT occurs because User32.dll does not free all of
its resources when it is unloaded.
As a result, the data table used to store the value for the symbol
COLOR_BTNFACE is corrupted. When the Regular DLL is loaded for the second
time, GetSysColorBrush returns NULL.
REFERENCES
For additional information, click the article number below
to view the article in the Microsoft Knowledge Base:
171145 PRB: Resource Leaks in System Components
Additional query words: GDI kbDLL kbKernBase
Keywords: kbarchitecture kbdll kbprb kbresource KB189383