# FirstEmissionBlockNumberAlreadySet (/docs/errors/chain/FirstEmissionBlockNumberAlreadySet)

`btcli sudo start` was issued for a subnet whose emissions have already been started. Check with `btcli sudo check-start`; if the subnet is already emitting, no action is needed.

Declared by the `SubtensorModule` pallet; it classifies to the semantic code [`already_exists`](/docs/errors/already-exists).

Declared at [`pallets/subtensor/src/macros/errors.rs#L201`](/code/pallets/subtensor/src/macros/errors.rs#L201).

## Remediation [#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 FirstEmissionBlockNumberAlreadySet`.