# Unreachable (/docs/errors/chain/Unreachable)

`announce_next_key` could not identify the current block author via the `FindAuthors` lookup, which should be impossible in a normally authored block. Check the block's author digest and the shield pallet's authorship wiring.

Declared by the `MevShield` pallet; it classifies to the semantic code [`internal`](/docs/errors/internal).

## Remediation [#remediation]

A chain-side invariant failed; nothing to fix client-side — report it if it persists

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