Solana activates Alpenglow, targeting 150ms transaction finality

Solana activated its Alpenglow consensus upgrade on Oct. 21, replacing the protocol it had used since 2020 and targeting transaction finality in about 150 milliseconds, according to Decrypt’s report citing core developer Anza. The target is down from about 12.8 seconds under the previous system, giving exchanges, merchants and apps a shorter wait before treating a transaction as irreversible.

What changes when a Solana transaction is final?

Alpenglow replaces TowerBFT, which validators used to agree on transaction order and finalize blocks. Validators completed the switch at slot 459,653,000, carrying Solana’s existing ledger forward, Decrypt reported.

Under TowerBFT, validators submitted votes as on-chain transactions. Alpenglow moves votes off-chain: validators exchange them directly, then combine signatures into a certificate recorded on-chain. Galaxy, which ran a validator on Alpenglow’s test cluster, says the protocol’s target is roughly 150 milliseconds to finality.

How could the upgrade affect Solana users?

Apps that wait for finality before completing a trade or payment could act sooner if the target holds on mainnet. Galaxy says users and builders settling through Solana may be able to rely on transactions in a fraction of the previous time.

Moving votes off-chain could also return block space to user activity. Galaxy says vote transactions made up roughly three quarters of the network’s processed transactions under the old system; that share will no longer be counted as on-chain vote traffic.

Does Alpenglow change staking rewards?

No change to how stake earns rewards is planned in this upgrade, according to Galaxy’s account of the migration. Validator voting costs do change: a flat 0.8 SOL admission ticket per roughly 24-hour epoch replaces per-vote fees, Galaxy says.

Sources

• Decrypt’s report citing core developer Anza — decrypt.co
• Galaxy’s account of the migration — galaxy.com