Solana activates Alpenglow, replacing TowerBFT with 150ms target

What changed on Solana? Anza’s Alpenglow consensus protocol went live on mainnet-beta on Oct. 21, retiring TowerBFT and targeting transaction finality in about 150 milliseconds, down from 12.8 seconds. The activation occurred at slot 459,653,000 at approximately 14:00 UTC, according to Anza’s announcement. For an exchange crediting a deposit or a merchant accepting payment, the change is about when a transaction becomes irreversible.

How does Alpenglow change transaction finality?

Alpenglow condenses Solana’s previous two-step path to finality into one, according to Anza. That is a change to the network’s consensus protocol, which validators use to agree on blocks; it does not change the point at which finality matters to an application. The Block reports that TowerBFT had been Solana’s consensus protocol since the network launched in March 2020.

Is 150 milliseconds a measured mainnet result?

Anza describes roughly 150 milliseconds as the new protocol’s finality speed, and says the migration was completed on the live network. The Block’s report likewise attributes the figure to Anza; the announcement describes Alpenglow as designed to deliver finality in that time. That distinction matters as you assess the upgrade: the activation is confirmed, while the cited reports do not establish sustained performance across varying live-network conditions.

Before mainnet, Alpenglow underwent public testing that included red teaming, penetration testing, migration rehearsals and a security competition, Anza said. The company also says further work is planned: Rotor would change how block data spreads, and geographically aware leader rotations aim to reduce handoff latency, but neither has a committed release date. The number to watch now is whether Solana sustains roughly 150-millisecond finality under live conditions.

References

• Anza’s announcement — prnewswire.com
• Block’s report — theblock.co