Hi, Since you mention linking to a library, did you properly export the symbols of that library ?

@vin212 said in How use MYSQL on QT: MySql .................................. no ... I continue, i try this commande : nmake Why? As you can see qmake did not find your libs, so why do you think 'nmake' will do anything for mysql? As written in the documentation look into the logs and see why the libs were not found or usable.

After building the VTK using Qt5.13.2, I uninstalled the Qt version since I already have 5.12.6. While running a sample code to check the VTK plugin I m getting the following linker error: 09:49:20: Running steps for project pcl_visualizer... 09:49:20: Starting: "/usr/bin/cmake" --build . --target all [ 20%] Automatic MOC and UIC for target pcl_visualizer [ 20%] Built target pcl_visualizer_autogen [ 40%] Linking CXX executable pcl_visualizer /usr/bin/ld: /usr/local/lib/libvtkGUISupportQt-7.1.so.1: undefined reference to `qt_version_tag@Qt_5.13' collect2: error: ld returned 1 exit status make[2]: *** [CMakeFiles/pcl_visualizer.dir/build.make:254: pcl_visualizer] Error 1 make[1]: *** [CMakeFiles/Makefile2:77: CMakeFiles/pcl_visualizer.dir/all] Error 2 make: *** [Makefile:84: all] Error 2 09:49:21: The process "/usr/bin/cmake" exited with code 2. Error while building/deploying project pcl_visualizer (kit: Desktop Qt 5.12.6 GCC 64bit) When executing step "CMake Build" 09:49:21: Elapsed time: 00:01. I m using CMake system and I tried the solution given here but it is not working. Should I create a different thread for this?