OrderNonceUsed

The object or state already exists; treat the goal as met or pick a different target

The nonce was already used or names different order bytes. For a new approval, choose a nonce greater than ApprovedOrders.highest_nonce; cancellation and expiry do not reset that watermark.

Declared by the LimitOrders pallet; it classifies to the semantic code already_exists.

Declared at pallets/limit-orders/src/lib.rs#L544.

Remediation

The object or state already exists; treat the goal as met or pick a different target

The same explanation is available in the terminal: btcli explain OrderNonceUsed.