Emergency Upgrader is basically the v2.1.8 upgrader for older versions of Unifier v2. Use this if you're stuck on v2.1.7 or older.
Run u!install https://github.com/UnifierHQ/emergency-upgrader
to install.
v2.0.0-v2.1.7 is required. v2.1.8 or newer are not supported.
Run u!emergency_upgrade
to upgrade Unifier.