Owncloud fails to load Qt-Platform xcb

Question

I try to run the owncloud client on my Debian desktop. I ran apt-get install owncloud-client to do so. But when I issue owncloud on the command line the following error appears:

This application failed to start because it could not find or load the
Qt platform plugin "xcb".

Available platform plugins are: linuxfb, minimal, minimalegl, offscreen.

Reinstalling the application may fix this problem.

But as I installed the package from repositories there should be no problem with broken library dependencies. To verify that I used ldd:

ldd /usr/bin/owncloud | grep xcb

which outputs:

libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f190be16000)
libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f190acd3000)
libxcb-glx.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0 (0x00007f190aaba000)
libxcb-dri2.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri2.so.0 (0x00007f190a8b5000)
libxcb-dri3.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri3.so.0 (0x00007f190a6b2000)
libxcb-present.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-present.so.0 (0x00007f190a4af000)
libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f190a2a8000)

What else can I do to find the problem?

Answer 1

Although all dependencies are fulfilled according to the command ldd, they actually are not. On Debian 8 I needed to install Qt5:

apt-get install qt5-default

This solved the problem.