Solana's Alpenglow Upgrade Goes Live, Cutting Finality to About 150 Milliseconds

Solana has completed the largest change to its core protocol since the network launched in 2020.

What happened

The Alpenglow consensus upgrade activated on mainnet at the start of epoch 1064 on Wednesday, Oct. 21, according to the Solana Foundation. Validators kept running the old system, TowerBFT, for about 5,000 slots before the new protocol took over at slot 459,653,000. The Solana Foundation said the handoff took about 900 milliseconds, with 446 of 654 participating validators voting to certify the starting block.

Anza, the engineering firm that built Alpenglow, said finality, the point at which a transaction can no longer be reversed, drops from about 12.8 seconds to roughly 150 milliseconds. CoinDesk noted that 150 milliseconds is a target under normal network conditions rather than a guarantee for every payment.

How it works

Under the old design, validators voted by sending transactions on the chain. With Alpenglow's voting protocol, called Votor, they send votes directly to one another and bundle them into certificates, so a block can be final after one or two voting rounds. A second piece, Rotor, which will change how block data spreads across the network, is planned but not yet scheduled.

What users notice

Wallets, apps and fees stay the same. CoinDesk pointed out one side effect: because validator votes are no longer recorded as transactions, dashboards that counted them will show lower transaction totals even if real user activity is unchanged.

Why it matters for crypto

Faster, near-instant settlement is aimed at exchanges, merchants and financial firms that wait for finality before treating money as moved. CoinDesk reported SOL fell 2.4% to around $104 on Thursday morning amid a broad market dip, so the upgrade has not yet shown up in price.