Errors/Chain errors
NewColdKeyIsHotkey
Check the argument values against the operation schema
The proposed new coldkey in a coldkey swap is already an existing hotkey account, which is not allowed. Check the Owner storage for the candidate key to confirm it is not registered as a hotkey, and pick a fresh coldkey.
Declared by the SubtensorModule pallet; it classifies to the semantic code invalid_argument.
Remediation
Check the argument values against the operation schema
The same explanation is available in the terminal: btcli explain NewColdKeyIsHotkey.