Trash cleanup interval: unit must be minutes, hours, or days
Admin settings save returned 400 Trash cleanup interval: unit must be minutes, hours, or days. when the unit is missing or not one of those three.
Why this happens
Cleanup interval needs a valid unit plus amount ≥ 1 (Trash cleanup interval: amount must be at least 1). Same unit set as keep-files-in-trash.
Diagnose and fix
1. Admin → Settings: choose minutes, hours, or days.
2. Set amount ≥ 1 and within the max for that unit.
3. See Trash cleanup interval / Trash retention.
4. See Keep files in trash: unit must be minutes, hours, or days.