This has happened when I tried to destroy the host

x ERROR: update or delete on table "hosts" violates foreign key constraint "tokens_host_id_fk" on table "tokens" DETAIL: Key (id)=(63) is still referenced from table "tokens".

If you feel this is an error with Foreman itself, please open a new issue with Foreman ticketing system, You would probably need to attach the Full trace and relevant log entries.
PG::Error
ERROR: update or delete on table "hosts" violates foreign key constraint "tokens_host_id_fk" on table "tokens" DETAIL: Key (id)=(63) is still referenced from table "tokens".
app/controllers/hosts_controller.rb:120:in `destroy'
app/models/concerns/foreman/thread_session.rb:33:in `clear_thread'