I had the same problem with QNAP TS-109 Pro II. I ran apt-get autoremove which removed packages listed bellow. It helped and method commands work not fine.
The following packages will be REMOVED: dctrl-tools debhelper debian-keyring debian-maintainers devscripts diffstat dput equivs fontconfig hicolor-icon-theme html2text libappconfig-perl libatk1.0-0 libatk1.0-data libauthen-sasl-perl libavcodec51 libavformat52 libavutil49 libcaca0 libcairo2 libcdparanoia0 libconvert-binhex-perl libcrypt-ssleay-perl libcucul0 libdatrie0 libdevel-symdump-perl libdirectfb-1.0-0 libdrm2 libfaad0 libfcgi-perl libfontenc1 libgif4 libgl1-mesa-glx libgsm1 libgtk2.0-0 libgtk2.0-bin libgtk2.0-common libio-socket-ssl-perl libjack0 liblircclient0 liblzo2-2 libmime-tools-perl libmpcdec3 libneon27-gnutls libnet-libidn-perl libnet-ssleay-perl libopenal1 libossp-uuid-perl libpango1.0-0 libpango1.0-common libparse-debcontrol-perl libpixman-1-0 libpod-coverage-perl libpostproc51 libsdl1.2debian libsdl1.2debian-alsa libserf-0-0 libsmbclient libsoap-lite-perl libspeex1 libsvn1 libswscale0 libsysfs2 libterm-size-perl libtest-pod-perl libthai-data libthai0 libtheora0 libtie-ixhash-perl libtiff4 libts-0.0-0 libvorbisenc2 libxcb-render-util0 libxcb-render0 libxcomposite1 libxcursor1 libxdamage1 libxext6 libxfixes3 libxfont1 libxft2 libxi6 libxinerama1 libxrandr2 libxrender1 libxv1 libxvmc1 libxxf86dga1 libxxf86vm1 lintian lsb-release mplayer-skin-blue patchutils strace subversion unzip wdiff x-ttcidfont-conf xfonts-encodings xfonts-utils 0 upgraded, 0 newly installed, 100 to remove and 31 not upgraded. After this operation, 95.6MB disk space will be freed. -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]

