Hi, I use Trinity on Arch Linux. I didn't use a display manager, but rather started Trinity and I3 through .xinitrc script (I don't know if it is relevant). After installing Trinity, some of GTK apps (Midori, dwb) failed to start in I3, with similar message: "Could not find mime type application/octet-stream" and segfaut. Didn't test in Trinity. First quick fix was to set an environment variable GSETTINGS_SCHEMA_DIR=/usr/share/glib-2.0/schemas but some other apps (SpaceFM) still segfaulted after many error messages. Then I disabled /etc/profile.d/trinity.sh and started it only when starting Trinity, which solved my problem.