/clock_and_orbit -IRTCM3/rtcm3torinex -I../qwt -I../qwtpolar -I.moc/release -o .obj/release/bncwindow.o bncwindow.cpp In file included from bncwindow.cpp:60:0: bncsslconfig.h:8:29: error: invalid use of incomplete type ‘class QSslConfiguration’ class bncSslConfig : public QSslConfiguration { ^ In file included from /usr/local/Trolltech/Qt-4.8.5/include/QtNetwork/qabstractnetworkcache.h:48:0,from /usr/local/Trolltech/Qt-4.8.5/include/QtNetwork/QtNetwork:7,from bncgetthread.h:29,from bncwindow.h:31,from bncwindow.cpp:44: /usr/local/Trolltech/Qt-4.8.5/include/QtNetwork/qnetworkrequest.h:56:7: error: forward declaration of ‘class QSslConfiguration’ class QSslConfiguration; ^ make[1]: *** [.obj/release/bncwindow.o] Error 1 make[1]: Leaving directory `/home/zzh/programs/BNC-2.11.0/BNC/src' make: *** [sub-src-make_default-ordered] Error 2 [zzh@zhaozhonghai BNC]$