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Solana sets Oct. 21 for Alpenglow upgrade targeting 150-millisecond finality
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- DeepHorus
Solana has scheduled its Alpenglow upgrade for Oct. 21, targeting roughly 150-millisecond transaction finality. The Solana Foundation’s timetable would replace TowerBFT, the voting system used since Solana launched in 2020. The 150-millisecond figure remains a target, with actual performance depending on network conditions.
The upgrade matters because a Solana payment can already appear successful almost immediately, but finality offers a stronger guarantee that it cannot be undone. Merchants waiting for that assurance before accepting payment, or bridges before releasing funds on another blockchain, could act sooner. Alpenglow therefore targets real payment and cross-chain settlement use cases.
Today, validators submit votes as transactions recorded on the blockchain. Alpenglow will let them exchange votes directly and combine approvals into a certificate that finalizes a block after one or two voting rounds. Because vote transactions disappear from blocks, Solana’s reported transaction count may fall sharply even if user activity stays flat.
Validators must prepare by using software built on Agave 4.3.0. Firedancer and Frankendancer operators will need to switch software temporarily because those programs will not support the initial migration. Removing vote transactions also changes validator costs: current voting charges of about 1 SOL per epoch will disappear, replaced by a flat admission fee of 0.8 SOL.
The migration is scheduled for epoch 1064, expected to begin around 15:00 UTC on Oct. 21. Solana will continue using its old voting system for the first 5,000 slots, short windows assigned for block production, before switching to Alpenglow roughly 18 minutes later. The activation may therefore create unusual headline transaction counts on day one.
If Alpenglow performs as targeted, Solana could offer faster settlement guarantees for payments, bridges and other applications. The rollout also carries operational risk, since validators must migrate software and alternative clients must temporarily change. The Oct. 21 activation will test Solana’s sub-second finality at scale.
