Porting App from Qt 4.8 to Qt 5.3 getting “ DSO mi

问题:

I built this project on qt 4.8 ubuntu 12.04(working) and now building it on qt 5.3 ubuntu 14.04 . I am getting following error while compiling

 error: mainwindow.o: undefined reference to symbol     
 '_ZN12QtConcurrent16ThreadEngineBase16setProgressValueEi'
 error: error adding symbols: DSO missing from command line
 /usr/lib/x86_64-linux-gnu/libQtCore.so.4:

.pro file

QT += serialport
 QT += widgets
 QT += network
 QT += core
 ...
 ...
 LIBS += "/usr/lib/x86_64-linux-gnu/libqjson.so.0"

no Idea what to do .. has any one came across this problem before.