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Solana activates Alpenglow, targeting 150ms finality

Solana activated Alpenglow on Oct. 21, replacing its old voting system with one that targets finality in about 150 milliseconds for payments and trades.

The Onchain Brief Editors2 min read
Solana activates Alpenglow, targeting 150ms finality

Anza’s Alpenglow upgrade went live on Solana mainnet on Oct. 21, replacing the network’s old consensus system and targeting transaction finality in about 150 milliseconds. Finality is the point when a transaction can no longer be reversed. The Solana Foundation’s Alpenglow page says the upgrade activated at the start of epoch 1064, at about 13:36 UTC.

The speed figure is a target, not a guarantee for every transaction. The Foundation says the previous system, TowerBFT, took about 12.8 seconds to make transactions final. The new system is designed to bring that wait down to roughly 150 milliseconds.

How does Alpenglow change Solana’s voting system?

Alpenglow lets validators send votes directly to one another and combine them into certificates. Validators are computers that check transactions and agree on the network’s records. Under TowerBFT, they sent votes as transactions on the chain. The CoinDesk report on the upgrade says the new system can finalize a block after one or two rounds of voting.

The change replaces TowerBFT, which Solana had used since its 2020 launch. Alpenglow took over from slot 459,653,000, according to the Foundation. It changes how validators agree on blocks; transaction execution, fees and wallet use stay the same.

Does 150 milliseconds mean every payment settles that fast?

No. The Foundation describes 150 milliseconds as an expectation, not a constant. Actual finality can vary with the voting conditions. The figure refers to the time for a transaction to become final, not the time between new blocks.

That distinction matters for apps and services that wait for a payment to be irreversible before releasing funds or goods. Faster finality could shorten that wait. The upgrade does not change how users send transactions, and the Foundation says existing wallets and apps continue to work as before.

What comes next for the upgrade?

Alpenglow’s first phase, Votor, is now live. A later phase called Rotor is planned to replace Turbine, Solana’s system for spreading block data across the network, but the Foundation has not scheduled it. It also says vote transactions no longer appear in blocks, so services that count them will need to adjust their activity measures.

The live activation confirms the protocol switch; it does not establish that every transaction now reaches finality in exactly 150 milliseconds. That timing remains a target, and the Foundation’s page does not give a separate measured average from mainnet.

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