I am using Boost 1.61 on Windows 10 with Qt 5.7.0 MinGW 32 bit compiler. I have been using the Boost for a while until I added Boost Log recently into my project, I got an undefined error on boost::filesystem whenever I have the following piece of code, the error will gone when I remove it: boost::log::add_file_log ( keyword::file_name = "sample.log", keyword::rotation_size = 10 * 1024 * 1024, keyword::time_based_rotation = boost::log::sinks::file::rotation_at_time_point(0,0,0), keyword::format =...