I can confirm the issue using Ubuntu MATE 18.04 LTS as server and Ubuntu MATE 16.04 LTS as client.
Applications work (open on client as expected): atril, brasero, charmap, cheese, gnome-disks, engrampa, eom, firefox, gdebi-gtk, libreoffice, mate-system-log, mate-calculator, mate-color-select, mate-dictionary, mate-font-viewer, mate-search-tool, mate-system-monitor, mate-terminal, pluma, mate-power-statistics, rhythmbox, shotwell, simple-scan, mate- screenshot, thunderbird, transmission-gtk, vlc, nautilus . Applications which do not work (open on server instead of on client): caja, deja-dup, blueman-manager . -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1815318 Title: mate 18.04.1 xserver won't open caja on local machine To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-mate/+bug/1815318/+subscriptions -- ubuntu-bugs mailing list firstname.lastname@example.org https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs