Solana to Deploy Alpenglow Upgrade on Oct. 21, Targeting 0.15-Second Transaction Finality

Solana will deploy a major network upgrade, called Alpenglow, on Oct. 21 to cut transaction finality time to about 0.15 seconds.

CoinDesk reported on Oct. 14 that the Solana Foundation had set the Alpenglow upgrade for Oct. 21 and plans to replace its existing TowerBFT consensus system with a new mechanism. The target transaction finality time is about 150 milliseconds, though actual processing speed may vary with network conditions.

The centerpiece of the upgrade is reducing the time it takes for a transaction to become irrevocably final. On Solana today, a transaction may appear to be processed quickly, but additional time is still required before it is confirmed as irreversible. With Alpenglow in place, payment providers and bridge services supporting cross-chain asset transfers should be able to verify transaction finality more quickly.

The validator voting process will also change. Until now, validators have recorded votes on-chain as transactions. Under the new system, validators will exchange votes directly with one another and combine approval results to finalize blocks. The process is designed to be completed in one or two voting rounds.

Because vote transactions will be removed from blocks, Solana's total transaction count may appear to fall sharply immediately after the upgrade. That does not necessarily mean actual user transactions or payment activity have declined; the foundation said the change in counting methodology could alter transaction-volume metrics.

Validator operations and the cost structure will also change. Participation in the upgrade requires software based on Agave 4.3.0. Firedancer and Frankendancer will not support the initial transition, so validators using those programs will need to switch software temporarily. The current voting fee of about 1 SOL per epoch will be eliminated and replaced with a fixed participation fee of 0.8 SOL.

The Alpenglow transition is scheduled to begin during Epoch 1064 at about 3 p.m. UTC on Oct. 21, equivalent to midnight in South Korea on Oct. 22. Solana plans to keep the existing consensus method for the first 5,000 slots, then switch to the new system about 18 minutes later.