DOCUMENT:Q103714 07-MAY-2001 [visualc] TITLE :PRB: LNK4016: Unresolved External Symbol "__doserrno" PRODUCT :Microsoft C Compiler PROD/VER:winnt:1.0,2.0,2.1 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - The Microsoft Foundation Classes (MFC), used with: - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1 ------------------------------------------------------------------------------- SYMPTOMS ======== Building a project with Visual C++ 1.0 generates the following unresolved link error for __doserrno: LNK4016: unresolved external symbol "__doserrno" Under Visual C++ 2.0 and 2.1, the following error is generated: LNK2001: unresolved external symbol "__doserrno" NOTE: This behavior does not occur in MFC 4.0 included with Visual C++ version 4.0 as MFC 4.0 supports multithreaded applications by default. CAUSE ===== This error may be caused by compiling an application with /MT or /MD (multithreaded options) and linking with the default versions of the Microsoft Foundation Class (MFC) libraries. The default versions of the MFC libraries were not built with the multithreaded C run-time library, which results in the above error. The MFC Libraries do not support calling MFC code from any thread other than the primary thread. You can make calls to the MFC libraries or global AFX helper functions only from the primary thread. RESOLUTION ========== The README.WRI file (installed by default in the \MSVCNT\ directory) describes how to remedy this problem. There are two possible solutions: - Rebuild a custom version of the MFC libraries with /MT or /MD defined. For information on building libraries, see the section "Using the New Run-Time Libraries" on page xx-xxi in the "Class Library Reference" manual. (Note that the README.WRI incorrectly references this section as the "Class Library User's Guide.") For example, to build the library NAFXCWD.LIB, use following the command: " NMAKE DEBUG=1 TARGET=W OPT="/MT" CODEVIEW=1 " (without the quotation marks) -or- - Rebuild the application using the single-threaded run-time library LIBC.LIB. To select the single-threaded run-time library, choose the Runtime category in the C/C++ Compiler Options dialog box. Additional query words: 1.00 2.00 2.10 LNK2001 ====================================================================== Keywords : Technology : kbAudDeveloper kbMFC Version : winnt:1.0,2.0,2.1 Issue type : kbprb ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.