Solana switches to new Alpenglow consensus system, cutting finality to about 150 milliseconds

The Solana blockchain replaced its original consensus protocol with a new system called Alpenglow on Wednesday 21 October, according to Anza, a core engineering firm for the network.

In a statement reported by The Block, Anza said Alpenglow reached Solana’s mainnet-beta at slot 459,653,000, at about 2:00pm GMT. The upgrade retires TowerBFT, the protocol Solana had used since its launch in March 2020.

Anza said Alpenglow merges Solana’s previous two-step confirmation process into one step, cutting the time until a transaction is final from about 12.8 seconds to about 150 milliseconds. It said this affects, for example, exchanges crediting deposits and merchants processing payments.

“This is the largest, most ambitious blockchain upgrade since ‘The Merge,’” Anza chief executive Brennan Watt said, referring to Ethereum’s 2022 switch to proof of stake. Anza first published the Alpenglow design in May 2025 and said the upgrade went through public testing, penetration testing, migration rehearsals and a security competition before going live.

Anza has outlined further changes, none with a confirmed release date, The Block reported. They include Rotor, which would change how block data moves across the network, and a research design called Quantumglow, which would replace Alpenglow’s elliptic-curve cryptography with hash-based signatures aimed at post-quantum security.

Solana’s SOL token was at about US$108.53 as of 5:46pm GMT on Wednesday, up 1.8% over 24 hours, according to CoinGecko data.