Solana’s Alpenglow Upgrade Arrives Oct. 21, Promising Finality in About 150 Milliseconds

One of the biggest changes to Solana since its 2020 debut now has a date. On Oct. 21, the network plans to retire TowerBFT, the voting mechanism it has run from the start, and replace it with Alpenglow. The goal is to make a payment irreversible within roughly 150 milliseconds. Merchants and cross chain bridges could release goods or funds sooner. Validators will stop posting votes as onchain transactions and will exchange them directly. Enough approvals get bundled into a certificate that locks in a block after one or two voting rounds.

What Validators and Data Watchers Should Expect

Because votes will no longer sit inside blocks, the headline transaction count could drop steeply on day one, even if user activity stays exactly the same. Operators must run software built on Agave 4.3.0. Firedancer and Frankendancer will not support the first migration, so their operators have to switch temporarily. The voting cost of roughly 1 SOL per epoch disappears, and a flat 0.8 SOL admission fee takes its place. An epoch is the span in which validators are given their network duties.

Alpenglow Migration Timing

The move is set for epoch 1064, expected to begin near 15:00 UTC. The old voting system will run for the first 5,000 slots, the short windows used for producing blocks. Alpenglow takes over about 18 minutes later.