Newer distros drop the python3-venv transitional package once it no longer resolves to a real pythonX.Y-venv candidate, which crashed sync.py's venv creation with a raw traceback. Prep now resolves the exact versioned package via apt-cache, and skips xfce4-genmon-plugin/plank/blueman on boxes with no xfconf-query so a non-XFCE box doesn't get noisy "unable to locate package" failures for a panel it'll never run. venv_python() also fails with an actionable message instead of an uncaught CalledProcessError. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>