Solana activates Alpenglow, targeting 150ms transaction finality

Solana activated Alpenglow on mainnet on October 21, replacing its consensus protocol with one designed to make transactions irreversible much faster. The Solana Foundation’s Alpenglow page says the upgrade targets about 150 milliseconds for finality, down from roughly 12.8 seconds under the old system.

The Foundation says the activation began with epoch 1064 at about 13:36 UTC. The Block reported that the switch to Alpenglow consensus took effect at slot 459,653,000, around 14:00 UTC, after validators handed over from TowerBFT. Finality is the point when a transaction can no longer be reversed.

How does Alpenglow aim to speed up finality?

Its first live phase, Votor, changes how validators agree on blocks. Under TowerBFT, validators recorded votes as transactions, and enough votes had to build up across 32 slots. The Foundation says Alpenglow has validators send votes directly to one another and combine them into certificates, which can finalize a block in one or two voting rounds.

The Block reported that Anza, a Solana core engineering firm, developed the protocol and said the transition replaced TowerBFT, which the network had used since its 2020 launch. The Foundation describes the 150-millisecond figure as a target. The upgrade’s design aims to make payment and trading settlement feel quicker, but that target does not by itself establish measured performance across the live network.

What changes for Solana users and apps?

The Foundation says transaction execution, programs, fees and wallets continue to work as before. Alpenglow changes how validators agree that a block is final, rather than how transactions run. Faster finality could let exchanges credit deposits and merchants treat payments as settled sooner, though the sources describe this as the expected effect of the target speed.

For developers who track or stream block data, the change is more involved. The Foundation says vote transactions no longer appear in blocks, and some streaming tools must account for multiple candidate blocks in a slot. It also says “confirmed” and “finalized” now describe the same state.

Is the full upgrade live yet?

Only Votor is live. The Foundation says Rotor, a later phase intended to replace the Turbine system that spreads block data across the network, is planned for a future release and has no schedule yet. The mainnet launch therefore marks the start of Alpenglow’s consensus changes, while that separate data-distribution update remains ahead.

Sources and documents

• Solana Foundation’s Alpenglow page — solana.com