- Solana validators retired TowerBFT at slot 459,653,000 on 21 October and handed consensus to Alpenglow.
- Votes from 446 of 654 participating validators certified the handover block, a switch the Solana Foundation timed at about 900 milliseconds.
- Validator votes no longer travel as transactions, and each voting validator now pays a flat 0.8 SOL fee per epoch.
Solana replaced its core voting system on Wednesday with Alpenglow, an upgrade that targets transaction finality in about 150 milliseconds instead of 12.8 seconds.
Anza, the core engineering team that built Alpenglow, said validators retired TowerBFT at slot 459,653,000, at about 14:00 UTC that day. TowerBFT had run Solana since its launch in March 2020. That switch happened on the live network, with the existing ledger carried forward.
Finality is the point at which a transaction can no longer be reversed. It is the moment exchanges, banks and merchants wait for before they treat an asset as moved. Under TowerBFT, Solana gave a conditional confirmation within seconds, with full finality coming later.
“This is the largest, most ambitious blockchain upgrade since ‘The Merge’ and Anza took it from a white paper to running on mainnet in under 18 months,” Anza chief executive Brennan Watt said.
Read more: AI Agents Hack More Than 100 Websites, Including Australian Targets, for Just US$5,000
How the Handover Worked
The upgrade’s feature gate switched on at the start of epoch 1064, at about 13:36 UTC, according to the Solana Foundation. TowerBFT kept running for another 5,000 slots after the gate, roughly 18 minutes. The last block of that window became the starting point for Alpenglow.
Votes from 446 of the 654 validators participating in the network certified that block. That handover between the two systems took about 900 milliseconds, the foundation said.
Under Alpenglow, validators send votes directly to each other and bundle them into certificates. With those certificates, a block becomes final after one or two rounds of voting. Alpenglow leaves transaction execution, formats and fees untouched, and wallets work as they did before.
Validators approved Alpenglow with more than 98% of votes in September 2025. Before mainnet, Anza put Alpenglow through red teaming, penetration testing and migration rehearsals, then launched it on testnet and devnet.
Validators Pay a New Fee
Because votes are no longer transactions, they have dropped out of Solana’s blocks. Under TowerBFT, voting cost each validator about 1 SOL per epoch in transaction fees.
In place of those fees, each voting validator now pays a Validator Admission Ticket, a flat 0.8 SOL per epoch taken from its vote account and burned. A validator that cannot pay is shut out of the following epoch and loses its rewards for it.
Mainnet validators also had to run Agave-based client software for the switch. The foundation said the Firedancer and Frankendancer clients were not supported for the migration.
Firedancer’s developers had earlier proposed scrapping the 60 million compute unit cap on each block once Alpenglow went live.
Anza has more changes planned, starting with Rotor, a new way of spreading block data across the network. Those changes have no committed date yet.
Related: Solana Treasury Firm SkyAI Sells Entire Holdings After Previously Accumulating Two Million SOL
Uncategorized#Solana #Activates #Major #Upgrade #Targeting #150Millisecond #Transaction #Finality1792748629
