Solana activated Alpenglow on October 21, 2026, replacing its TowerBFT consensus system, according to core software team Anza. The upgrade targets block finality of about 150 milliseconds, down from 12.8 seconds, but real-world mainnet results had not yet established whether it meets that target. Rotor, the upgrade’s data-dissemination component, was not scheduled for mainnet, so the rollout remained incomplete.
Alpenglow lets validators exchange votes directly and bundle them into off-chain certificates. It also replaces daily vote fees of roughly 2 SOL with a fixed 0.8 SOL fee per epoch, about every 24 hours. Anza projects this will cut validator operating costs by about 60%.
