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Solana Alpenglow Goes Live, Targeting 150ms Finality

Solana activated Alpenglow on mainnet on Oct. 21, replacing TowerBFT and targeting 150-millisecond finality through direct validator votes and certificates.

Uruguay Can Editorial

Solana Alpenglow Goes Live, Targeting 150ms Finality

Solana’s TowerBFT consensus took about 12.8 seconds to finalize a block; on Oct. 21, the network switched to Alpenglow, which targets roughly 150 milliseconds. The Solana Foundation’s upgrade tracker says the change began in epoch 1064 at approximately 13:36 UTC, with Alpenglow consensus taking over at slot 459,653,000.

What changed in Solana’s consensus?

Alpenglow replaces TowerBFT, the voting protocol Solana had used since its 2020 launch. Under the old system, validators sent votes as transactions and a block became final after enough votes accumulated over 32 slots. With Alpenglow’s first phase, called Votor, validators send votes directly to one another and combine them into certificates. The block can then become final after one or two rounds of voting, according to the Foundation.

The change affects how validators agree on a block, while transaction execution stays the same: Solana’s programs, fees and SVM—the software environment that runs those programs—are unchanged. That distinction matters if you build on the network: faster finality is the target, but the upgrade does not change how an application’s transaction runs.

Does 150 milliseconds mean every transaction is settled that fast?

It is the protocol’s target for finality, not a guarantee that every transaction will settle in exactly that time. The Block reported Anza’s confirmation of the mainnet handoff and described the reduction from about 12.8 seconds to roughly 150 milliseconds. The faster target could matter to exchanges crediting deposits and merchants processing payments, where waiting for a transaction to become irreversible affects when they can act on it.

What comes next for the upgrade?

Alpenglow is rolling out in two phases. Votor is now live; the planned second phase, Rotor, would replace Turbine, Solana’s system for spreading block data across the network. The Foundation says Rotor has no scheduled release date. So the live change delivers the new voting and finality mechanism, while the network’s block-propagation upgrade remains ahead.

Sources