[FIXED] Can't find Qt5::OpenGL with cmake

Posting this because I want to share the solution.

Got this error when trying to cmake OpenCV :

-- Found PNG: /usr/lib/arm-linux-gnueabihf/libpng.so (found version "1.2.50") 
-- Looking for /usr/include/libpng/png.h
-- Looking for /usr/include/libpng/png.h - found
-- Found OpenEXR: /usr/lib/arm-linux-gnueabihf/libIlmImf.so
CMake Error at /usr/lib/arm-linux-gnueabihf/cmake/Qt5OpenGL/Qt5OpenGLConfig.cmake:27 (message):
  The imported target "Qt5::OpenGL" references the file

     "/usr/lib/arm-linux-gnueabihf/libQt5OpenGL.so.5.3.2"

  but this file does not exist.  Possible reasons include:

  * The file was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and contained

     "/usr/lib/arm-linux-gnueabihf/cmake/Qt5OpenGL/Qt5OpenGLConfig.cmake"

  but not all the files it references.

Call Stack (most recent call first):
  /usr/lib/arm-linux-gnueabihf/cmake/Qt5OpenGL/Qt5OpenGLConfig.cmake:44 (_qt5_OpenGL_check_file_exists)
  /usr/lib/arm-linux-gnueabihf/cmake/Qt5OpenGL/Qt5OpenGLConfig.cmake:134 (_populate_OpenGL_target_properties)
  cmake/OpenCVFindLibsGUI.cmake:26 (find_package)
  CMakeLists.txt:601 (include)

When trying to reinstall qt (apt-get install qt5-default) got a message saying it was already installed, so I solved it by adding a symlink:

ln -s /usr/lib/arm-linux-gnueabihf/libQt5OpenGL.so.5.3.2 /usr/lib/arm-linux-gnueabihf/libQtOpenGL.so

 If you can't find your QtOpenGL library just run a find / -name "libQt*" query and see if anything similar comes up.

Edited January 4, 20188 yr by Tony