Solana validators switched the network to the Alpenglow consensus protocol on Wednesday. Anza says transactions now become irreversible in about 150 milliseconds instead of 12.8 seconds. Further upgrades are planned, but none has a committed date.
Solana's largest consensus upgrade since the network launched in 2020 went live on Wednesday, according to core engineering team Anza. The change cuts the time a transaction needs to reach finality from about 12.8 seconds to roughly 150 milliseconds.
Anza CEO Brennan Watt called it "largest, most ambitious blockchain upgrade since 'The Merge'", according to Decrypt.
Validators retire TowerBFT at slot 459,653,000
Validators retired TowerBFT, the consensus protocol Solana had used since March 2020, at slot 459,653,000 at around 14:00 UTC. They switched systems on the running network while carrying its existing ledger forward.
Under TowerBFT, Solana gave a conditional confirmation within seconds but took about 12.8 seconds to reach full finality, Decrypt reported. Alpenglow condenses the previous two-step process into a single step, according to The Block, for exchanges crediting deposits and merchants processing payments.
Bitcoin.com News adds that Alpenglow does not change how Solana executes transactions, so existing applications, smart contracts and transaction fee mechanisms remain intact. Because validator votes no longer appear as ordinary blockchain transactions, the outlet noted that reported transaction counts could decline without any drop in user activity.
Testing came before mainnet
Before reaching mainnet, Alpenglow went through public testing, including red teaming, penetration testing, repeated migration rehearsals and a security competition. Anza's research team, led by ETH Zurich professor Roger Wattenhofer, published the design in May 2025.
Validators approved the upgrade in September 2025, voting 98% in favor of SIMD-0236. Under the new protocol, validators send votes directly to each other instead of writing them into later blocks.
More upgrades have no dates
Anza is also working on further changes. Rotor would change how block data spreads across the network, while geographically aware leader rotation aims to reduce delays between block producers.
Quantumglow, a research design, would swap Alpenglow's elliptic-curve cryptography for hash-based signatures to guard against quantum computers while keeping the same finality speed. None of these changes has a committed date.
Sources: Decrypt, The Block, Bitcoin News
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