LNK1104 Error when adding Boost library to Qt project - c++

Question

M'kay so I'm new to Qt and I'm trying to include the boost/filesystem lib to my project. However, when I try to build it, I always get this error:
LNK1104: File "libboost_filesystem-vc140-mt-1_61.lib" cannot be
opened.
Now, I know that this library needs to be build beforehand, so, as described on the Boost-Website I made:
bootstrap
.\b2
and it built just fine. I also used the Qt dialog to add the libary to my project, my .pro-file looks like this:
QT += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = ProjectName
TEMPLATE = app
SOURCES += main.cpp\
mainwindow.cpp \
someclass.cpp \
someclass2.cpp
HEADERS += mainwindow.h \
someclass.h \
someclass2.h
FORMS += mainwindow.ui
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/libarys -llibboost_filesystem-vc140-mt-1_61
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/libarys -llibboost_filesystem-vc140-mt-1_61
else:unix: LIBS += -L$$PWD/libarys -llibboost_filesystem-vc140-mt-1_61
INCLUDEPATH += $$PWD/boost
DEPENDPATH += $$PWD/boost
Apparently, I did something wrong, but I can't figure out, WHAT exactly it is. The internet knows the problem, but it seems there's no "easy" solution to it.

Answer 1

Turned out, my project didn't like the lib-version.
I rebuilt my lib files:
>b2 --build-dir="destination/directory" toolset=msvc --build-type=complete link=static threading=multi --with-filesystem stage
Then, I used the library in
release/link-static/runtime-link-static/threading-multi/
Which is:
libboost_filesystem-vc140-mt-s-1_61
And re-ran qmake for the .pro-file. Then built and executed the application and the error is gone.