Solana has set Oct. 21 for the Alpenglow consensus upgrade, which aims to cut transaction finality from about 12.8 seconds to 150 milliseconds.
The timetable comes from the Solana Foundation, and the date was announced by Solana core developer Anza. Alpenglow replaces TowerBFT, the voting system the network has run since its 2020 launch, making it the biggest consensus change in Solana’s history. Validators will exchange votes directly off-chain and combine approvals into aggregate certificates that finalize a block after one or two voting rounds, instead of submitting votes as transactions on-chain.
The 150-millisecond figure is a target, and actual finality will depend on network conditions. Even so, that would put settlement certainty close to what payment-card rails offer today.
One side effect on launch day: because vote transactions disappear from blocks, headline transaction counts may drop sharply even if user activity stays flat.
Migration is scheduled for epoch 1064, expected around 15:00 UTC on Oct. 21, per the Foundation timetable. The current voting system runs for the first 5,000 slots of the epoch, about 18 minutes, before the switch. Alpenglow was already activated on testnet on Sept. 24 and devnet on Sept. 25.
Validators need software built on Agave 4.3.0 for the migration. Firedancer and Frankendancer operators will have to switch clients temporarily, since neither supports the initial migration. Voting costs also change: the roughly 1 SOL per epoch charge goes away in favor of a flat 0.8 SOL admission fee.
