The page loaded but the application code never ran, so nothing has been rendered. This is a client-side failure: the application server is very likely fine and will not have logged an error of its own.
Where to look, in this order:
/assets/…js and read its status
code:docker compose -f docker-compose.yml -f compose.site.yml logs proxy
in /opt/adapt at a site, or
./scripts/run.sh --logs in a dev checkout.
A hard reload (Ctrl/Cmd‑Shift‑R) rules out a stale cached bundle.