Trash cleanup interval: amount must be at least 1
Admin settings save returned 400 Trash cleanup interval: amount must be at least 1. when the amount is missing, non-numeric, or less than 1.
Why this happens
Cleanup interval needs a positive integer (with a valid unit). Sibling (Phase 64): unit must be minutes, hours, or days. Related keep-in-trash amount rules use the same shape.
Diagnose and fix
1. Admin → Settings: set cleanup amount ≥ 1 and a valid unit.
2. Stay under the max for that unit if the UI/API enforces one.
3. See Trash cleanup interval / Trash retention.
4. See Keep files in trash: enter a number of at least 1 for retention amount.