Solana switched its mainnet to the Alpenglow consensus protocol on Wednesday, retiring TowerBFT, the voting system the network had used since 2020.
The official Solana account posted at 13:59 UTC that Alpenglow was live on mainnet. Anza, the developer behind the protocol, had declared it live five minutes earlier. The chain’s own records also show the transition took place.
Chain data shows how the cutover happened
Queries by Unchained to Solana’s public mainnet RPC found that the final block from the TowerBFT era was slot 459,652,999, stamped at about 13:54:00 UTC. Alpenglow’s genesis certificate points to that block.
Eight slots then passed without a block before slot 459,653,008 appeared at 13:54:03 UTC. Block heights then continued in sequence, with no sign of a rollback.
The timing came in earlier than Anza’s own projections. Unchained had reported on Oct. 14 that the team first set the switch for about 14:50 UTC. Solana Compass later showed the estimate had been moved forward to around 14:00 UTC.
Finality claim set at 150 milliseconds
Both Anza and the Solana account attached the same figure to the change: finality was reduced from 12.8 seconds to 150 milliseconds.
The 12.8-second figure reflects Solana’s earlier 400-millisecond slots. The Solana Foundation has said slot times were later reduced to 200 milliseconds. Galaxy, which operates Solana validators, wrote in a pre-launch explainer that finality had already fallen to roughly 6 seconds under the shorter slots.
What changes for validators
Under Alpenglow, validators no longer submit votes as transactions. Votes now move between nodes as BLS-signed messages and are aggregated into certificates, which frees blockspace for users.
A block can reach finality in one round if 80% of stake votes for it, or in two rounds at 60%.
The design is intended to keep operating with as much as 20% of stake acting maliciously and another 20% offline.
Fee model and reported network metrics will change
Instead of paying per-vote fees, each voting validator now pays a flat 0.8 SOL per epoch.
Galaxy had noted that vote transactions accounted for roughly three quarters of Solana’s traffic. The Solana Foundation expects reported transaction counts and TPS to drop sharply.
Wednesday’s rollout covers Votor, not Rotor
The switch completed on Wednesday covers Votor, the voting half of the design. Rotor, which is meant to replace Turbine’s block propagation system, is planned for a later phase, with no date set.