Solana activated the Alpenglow consensus upgrade on its mainnet on October 21, replacing the previous TowerBFT mechanism. The update targets a finality time of approximately 150 milliseconds and merges the confirmed and finalized states into a single state for transactions.
The first phase of the upgrade, known as Votor, enables validators to exchange votes directly and aggregate them into certificates, allowing finalization in one or two voting rounds. The second phase, Rotor, which handles block propagation, remains unscheduled, while transaction execution and fee mechanics remain unchanged.
Key facts
- Solana activated Alpenglow at slot 459,653,000 on October 21.
- The upgrade replaces TowerBFT with a new consensus design targeting 150-millisecond finality.
- Confirmed and finalized blocks are now treated as the same state under the new protocol.
- The Votor phase allows validators to finalize blocks in one or two voting rounds.
- The Rotor phase for block propagation is not yet scheduled for release.
- Transaction execution via the Solana Virtual Machine and fee mechanics remain unchanged.
Why it matters
The upgrade shortens the time until a transaction becomes irreversible, concentrating gains in workflows that wait for full finality before releasing assets or recognizing settlement.