My project (windows, vs2008, debug) was linking successfully under boost-39. When I switched to boost 41 version the linker started to complain about missing lib (fatal error LNK1104: cannot open file 'libboost_filesystem-vc90- mt-gd-1_39.lib'). My linker properties does not specify the library explicitly, just the path to boost libraries. The path had been changed to boost 41 (I have $BOOST system var that both compiler and linker properties refer to) and there are corresponding libraries under the same relative path in boost 41 (libboost_filesystem-vc90-mt-gd-1_41.lib). Specifying new library explicitly in the linker properties did not help. I renamed old "39" directory and both compiler and linker are referring to boost via system variable. I double checked that this system variable points to the new "41" directory. Compiling completes sucessfully, but linker fails. How can I correct the problem?