I need using qt5.12.12 with msvc2017 and downloaded common dependencies from ftp mirror. But take error in Kit tab in QtCreator. "Qt version is not properly installed, please run make install" Then i installed offline qt 5.12.12 and compare two qmake.exe. Its difference by internal variables: qt_prfxpath, qt_epfxpath, qt_hpfxpath. In ftp case its equals for 'c:/Users/qt/work/install', in offline installer case - 'C:\Qt\Qt5.12.12\5.12.12\msvc2017_64'. For disable error set your according qt path by patch.