Errors/Chain errors
CannotUseSystemAccount
Sign with the key or origin that owns the target object, then retry
The hotkey supplied for registration, hotkey swap, or subnet-owner-hotkey assignment is a reserved subnet system account. Use a regular user-generated hotkey instead; system accounts are derived per-subnet and rejected by is_subnet_account_id.
Declared by the SubtensorModule pallet; it classifies to the semantic code not_authorized.
Remediation
Sign with the key or origin that owns the target object, then retry
The same explanation is available in the terminal: btcli explain CannotUseSystemAccount.