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Solana replaced its long-standing TowerBFT consensus with Alpenglow on October 21, 2026, in what the Agave client’s lead developer Anza called the “greatest upgrade in Solana’s history,” according to Cointribune. The new protocol targets finality of roughly 150 milliseconds, compared with about 12.8 seconds before.
The changeover began at the start of epoch 1064. The network kept TowerBFT running for the first 5,000 slots of that epoch, roughly 18 minutes, as a preparatory step, and the transition completed at slot 459653000. Cointribune reported that 654 validators took part and that no network-wide outage occurred.
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Key facts
- Alpenglow replaced TowerBFT on Solana mainnet at slot 459653000, at the start of epoch 1064.
- The targeted finality moves from 12.8 seconds to about 150 milliseconds; 654 validators participated in the switch, which took about 900 milliseconds.
- Votor runs two voting paths: a block can finalize in one round with 80% stake participation, or after two rounds at 60% participation.
- Each admitted validator pays a ticket of 0.8 SOL per epoch; an unpaid fee blocks voting and block production in the following epoch.
- Anza’s design lets Alpenglow tolerate 20% of stake offline and 20% hostile at once, whereas TowerBFT relied on a limit under one-third malicious participation.
What changed in the voting process
Under Votor, validator votes are no longer recorded as ordinary on-chain transactions. Validators exchange signed messages directly using BLS signatures, and multiple signatures can be aggregated into one compact certificate, which frees block space for user operations.
During the critical phase of the handoff, blocks temporarily stopped including user transactions and carried only the necessary votes, a precaution meant to allow a rollback without invalidating a user-signed operation. Transactions resumed once the genesis certificate was formed and nodes passed consensus to Votor.
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Operational guidance differed across reports. According to Crypto.news, the Solana Foundation’s checklist instructed validators to run version 4.3.2 of Agave, Jito-Solana or Harmonic Salsa before epoch 1064, and Firedancer and Frankendancer were not supported during the migration. Crypto.news also reported that Quicknode estimated activation near 14:50 UTC but moved its estimate forward to 13:20 UTC, and that during the handoff some transaction submissions could return a “node unhealthy” preflight error while data streams may disconnect once. AMBCrypto reported that the Foundation listed the activation switch as active on October 21, and that ordinary holders needed no token migration or upgrade transaction.
Part of the design is still to come
The October 21 activation covered Votor, not the full Alpenglow design. Rotor, a future block propagation system meant to replace Turbine, is scheduled for a later phase with no fixed date, per Cointribune. The economic model for validators also changed: off-chain votes remove the old per-vote transaction fees, replaced by the 0.8 SOL per-epoch validation ticket.
Why it matters
Faster finality changes when a payment or trade is treated as irreversible. Cointribune identifies payments, decentralized exchanges and applications needing quick certainty as the main beneficiaries, while warning that application interfaces and servers add their own delays. Crypto.news adds that some RPC nodes may learn of finality later than validators participating directly in consensus, because unstaked nodes default to receiving certificates in later blocks. Governance preceded the rollout: Crypto.news reported that the SIMD-0326 proposal passed in September 2025 with 98.27% support from votes cast, a figure covering 52% of stake rather than the whole validator set.
What to watch
The coming weeks will test whether observed finality holds near 150 milliseconds during periods of high activity, with network stability, validator participation and the later deployment of Rotor all bearing on the outcome, Cointribune reported. AMBCrypto noted SOL traded near $106.85 on October 21, and that the $108–$109 range was the next recovery area to watch. Nothing here is financial advice, and crypto markets are volatile and uncertain.
Reported by cointribune.com.
Sources: Cointribune, Crypto.news, Ambcrypto