The libraries are installed to /opt and so they shouldn't interfere with the rest of the system.
To use the Qt 5.6 libraries, owncloud can be started as follows:
LD_LIBRARY_PATH=/opt/qt56/lib/ /usr/bin/owncloud
Note: I am not sure if Qt 5.6 is officially supported by owncloud (there are at least problems on OSX - see here for a discussion: https://github.com/owncloud/client/issues/3449), but for me everything seems to work. This also fixes the issue that the owncloud icon does not appear in the system tray.
Until the issue is properly resolved and Ubuntu's Qt packages are updated, I have found that installing the Qt 5.6 libraries from the PPA here https:/ /launchpad. net/~beineri/ +archive/ ubuntu/ opt-qt56- xenial solves this problem.
The libraries are installed to /opt and so they shouldn't interfere with the rest of the system.
To use the Qt 5.6 libraries, owncloud can be started as follows:
LD_LIBRARY_ PATH=/opt/ qt56/lib/ /usr/bin/owncloud
Note: I am not sure if Qt 5.6 is officially supported by owncloud (there are at least problems on OSX - see here for a discussion: https:/ /github. com/owncloud/ client/ issues/ 3449), but for me everything seems to work. This also fixes the issue that the owncloud icon does not appear in the system tray.