Solana schedules Alpenglow for Oct. 21, targets 150ms finality

Solana has set Oct. 21 to activate Alpenglow, replacing TowerBFT’s roughly 12.8-second finality with a target of about 150 milliseconds. The Solana Foundation’s Alpenglow upgrade page places activation at the start of epoch 1064, expected around 15:00 UTC.

Finality is the point when a transaction can no longer be reversed. The shorter target could let services that wait for that assurance, such as exchanges and merchants, act sooner, although the target is not a guarantee of performance under every network condition.

How will Alpenglow change Solana’s consensus?

Alpenglow replaces TowerBFT with a new consensus protocol that moves validator votes off the blockchain. As CoinDesk reported, validators currently record votes as transactions; under Alpenglow, they exchange votes directly and combine approvals into certificates that finalize blocks.

That change could also lower Solana’s reported transaction count because validator votes will no longer appear in blocks. A lower count after activation would not by itself show that user activity had fallen.

What happens during the Oct. 21 transition?

The network will keep using TowerBFT for the first 5,000 slots of epoch 1064, about 18 minutes after the epoch begins, before Alpenglow takes over. The Foundation says the start time is an estimate because epoch timing can shift.

What do validators need to prepare?

Validator operators need to complete two steps before activation:

1. Run an Agave-based client built on version 4.3.0; Firedancer and Frankendancer will not support the initial migration.

2. Keep at least 0.8 SOL in the vote account, above its rent-exempt minimum, to pay the validator admission fee.

Sources

• Alpenglow upgrade page — solana.com
• CoinDesk reported — coindesk.com