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Solana’s Alpenglow upgrade goes live, targeting 150ms finality

Solana activated Alpenglow on Oct. 21, replacing TowerBFT with validator-to-validator voting that targets 150ms finality and changes how operators pay to vote.

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Solana’s Alpenglow upgrade goes live, targeting 150ms finality

Solana had relied on TowerBFT since its 2020 launch; on Wednesday, Oct. 21, it switched mainnet to Alpenglow, a new consensus protocol designed to make transactions final much faster. The Solana Foundation’s Alpenglow update says the upgrade became active at the start of epoch 1064, at about 13:36 UTC, with the new consensus taking over at slot 459,653,000.

Consensus is how validators agree on transaction order and when a transaction can no longer be reversed. Solana says Alpenglow targets finality in about 150 milliseconds, down from roughly 12.8 seconds under TowerBFT. The change affects how blocks are confirmed; the network’s transaction execution, programs and fee mechanics remain the same.

How does Alpenglow change validator voting?

Under TowerBFT, validators sent votes as transactions on the chain, and votes accumulated over multiple slots. Alpenglow’s Votor protocol sends votes directly between validators and bundles them into certificates, allowing a block to become final after one or two voting rounds. The Block reported the mainnet handoff at slot 459,653,000 and described the shift as a move from about 12.8 seconds to roughly 150 milliseconds.

For you as a user, Solana says sending transactions and using wallets or apps work as before. The shorter target could make confirmations feel closer to an immediate settlement, though it does not change how often blocks are produced.

What changes for Solana validators?

Operators need a supported client and a funded vote account to keep voting and producing blocks. The Solana Foundation lists these requirements:

  1. Run an Agave-based client, such as Agave v4.3.2, Jito-Solana or Harmonic Salsa.
  2. Keep at least 0.8 SOL above the vote account’s rent-exempt minimum to pay the Validator Admission Ticket fee each epoch.

The fee paid at the start of one epoch covers participation in the next; if it is unpaid, the validator does not vote or produce blocks for that following epoch. Alpenglow is also rolling out in stages: Votor is live, while Rotor, which is intended to change how block data spreads across the network, has no scheduled release yet.

Sources