Solana sets Oct. 21 date for Alpenglow consensus switch

Solana plans to activate its Alpenglow consensus upgrade on Oct. 21, targeting transaction finality in about 150 milliseconds, according to the Solana Foundation’s upgrade page. Finality is the point at which a transaction is considered settled and no longer reversible under the network’s rules.

• Activation is planned for epoch 1064, expected to start at about 15:00 UTC.
• Alpenglow targets roughly 150 milliseconds to finality, down from about 12.8 seconds.
• The network will keep using its current system for the first 5,000 slots of the epoch, about 18 minutes.

The 150-millisecond figure is a target, and actual performance will depend on network conditions, CoinDesk reported after reviewing the updated timetable. The change affects how validators agree on blocks, while transaction execution, programs and fees are set to remain the same, according to the Foundation.

How will Alpenglow change validator voting?

Alpenglow will replace TowerBFT, Solana’s current consensus system, with a process that lets validators send votes directly to one another. They will combine approvals into certificates, allowing a block to become final after one or two rounds of voting, the Foundation says.

Today, validator votes are recorded as transactions on the blockchain. Under Alpenglow, votes will no longer appear in blocks. That means reported transaction counts could fall sharply even if people continue trading and making payments at the same pace, CoinDesk reported.

The lower finality target could matter when a business needs a stronger settlement guarantee before acting. CoinDesk cited merchants accepting payments and bridges releasing funds on another blockchain as cases where faster confirmation could help. The timing remains a target rather than a guarantee for every transaction.

When does the network actually switch?

The Foundation’s schedule puts the feature activation at the start of epoch 1064, around 15:00 UTC on Oct. 21. Solana will then continue running TowerBFT for the first 5,000 slots, or roughly 18 minutes, before Alpenglow consensus takes over.

The Foundation says the time is an estimate because epoch start times can drift with slot timing. The switch to the new voting system is therefore expected after the epoch begins, rather than at the precise 15:00 mark.

What do validator operators need to prepare?

Validators need to run an Agave-based client built on version 4.3.0 before activation, according to the Foundation. The supported clients listed are Agave, Jito-Solana and Harmonic Salsa. Firedancer and Frankendancer are not supported during the migration, so operators using them will need to switch software temporarily.

Operators also need at least 0.8 SOL above the vote account’s rent-exempt minimum to cover the Validator Admission Ticket fee. The Foundation says the fee is charged at the start of each epoch to pay for the next one; without it, a validator will not vote or produce blocks in that following epoch.

For users, the Foundation says wallets and apps should keep working as they do today. Alpenglow changes the network’s consensus process and the speed at which blocks become final, while leaving transaction execution untouched.

Sources and documents

• Solana Foundation’s upgrade page — solana.com
• reported after reviewing the updated timetable — coindesk.com