Solana’s Alpenglow upgrade set for Oct. 21

Solana users should be able to rely on transactions becoming irreversible much sooner after the Alpenglow upgrade, scheduled for Oct. 21. The [Solana Foundation’s upgrade page](https://solana.com/nl/upgrades/alpenglow) says the network targets finality in roughly 150 milliseconds, down from about 12.8 seconds today.

For wallet users, the change is faster settlement without a new setup step or a change to transaction fees.

What changes when Alpenglow goes live?

Alpenglow replaces TowerBFT, Solana’s current consensus protocol, which is how validators agree on transaction order and when a block can no longer be reversed. Under the new Votor protocol, validators send votes directly to each other and combine approvals into certificates; the Solana Foundation says a block can then become final after one or two voting rounds. The 150-millisecond figure is a target, not a guarantee for every transaction or network condition.

The change affects how quickly a transaction reaches finality, rather than how a wallet signs or sends it. The Foundation says transaction execution, programs and fee mechanics remain unchanged, and wallets and apps keep working as they do now. That means users do not need to migrate their wallets ahead of activation.

What do validators need to prepare?

Validators must run a client built on Agave 4.3.0 before epoch 1064 begins, expected around 15:00 UTC on Oct. 21. The Foundation lists Agave, Jito-Solana and Harmonic Salsa as supported for the migration; operators running Firedancer or Frankendancer must switch clients temporarily. Validators also need at least 0.8 SOL above the rent-exempt minimum in their vote account to pay the new admission fee.

According to [CoinDesk’s report on the migration](https://www.coindesk.com/tech/2026/10/14/solana-sets-oct-21-for-alpenglow-upgrade-targeting-150-millisecond-finality), that flat 0.8 SOL fee per epoch replaces voting charges of roughly 1 SOL per epoch. The fee comes from the vote account and is paid one epoch ahead; if it is unpaid, the validator will not vote or produce blocks in the following epoch. This is an operator cost, while the Foundation says user transaction fees are not changing.

Will Solana’s transaction counts change?

Yes: validator votes will no longer be recorded as transactions in blocks, so reported transaction counts can fall even if user activity holds steady. The Foundation advises services that count or parse block transactions to reset their baselines after activation. Solana will also keep TowerBFT running for the first 5,000 slots of epoch 1064, with the consensus switch expected about 18 minutes after the epoch starts.