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Linker Tools Error LNK2005


The latest version of this topic can be found at Linker Tools Error LNK2005.

symbol already defined in object

The given symbol, displayed in its decorated form, was multiply defined.

For more information, see the Knowledge Base articles:

  • "LNK2005 Errors When Link C Run-Time Libraries Are Linked Before MFC Libraries" (Q148652)

  • "Global Overloaded Delete Operator Causes LNK2005" (Q140440)

  • "LNK2005 Errors on New and Delete When Defining _ATL_MIN_CRT" (Q184235).

You can find Knowledge Base articles on the MSDN Library CD-ROM or at

This error is followed by fatal error LNK1169.

To fix by checking the following possible causes

  1. Mixing static and dynamic libraries when also using /clr.

  2. The symbol is a packaged function (created by compiling with /Gy) and was included in more than one file but was changed between compilations. Recompile all files that include symbol.

  3. The symbol is defined differently in two member objects in different libraries, and both member objects were used.

  4. An absolute is defined twice, with a different value in each definition.

  5. A header file declared and defined a variable. Possible solutions include:

    • Declare the variable in .h: extern BOOL MyBool; and then assign to it in a .c or .cpp file: BOOL MyBool = FALSE;.

    • Declare the variable static.

    • Declare the variable selectany.

  6. If you use uuid.lib in combination with other .lib files that define GUIDs (for example, oledb.lib and adsiid.lib). For example:

    oledb.lib(oledb_i.obj) : error LNK2005: _IID_ITransactionObject  
    already defined in uuid.lib(go7.obj)  

    To fix, add /FORCE:MULTIPLE to the linker command line options, and make sure that uuid.lib is the first library referenced.