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Solana Sets Oct. 21 Alpenglow Activation for 150ms Finality

Solana’s Alpenglow consensus upgrade is set for Oct. 21, replacing TowerBFT with a vote-certificate system that targets 150-millisecond finality.

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Solana Sets Oct. 21 Alpenglow Activation for 150ms Finality

Solana’s current consensus takes about 12.8 seconds to finalize a transaction; the Solana Foundation says Alpenglow will begin activating Oct. 21, targeting roughly 150 milliseconds. The date marks a planned change to how validators agree that a block is final, a stronger settlement signal for anyone waiting to accept a payment or release funds. The Foundation’s Alpenglow upgrade page puts activation at the start of epoch 1064, around 15:00 UTC.

How will Alpenglow change finality?

Alpenglow replaces TowerBFT, Solana’s current validator voting system, with Votor, where validators send votes directly to each other and combine approvals into certificates. According to the Foundation, a block can then become final after one or two voting rounds, instead of waiting for votes to stack across 32 slots. The 150-millisecond figure is a target, not a guaranteed result: actual performance will depend on network conditions.

That distinction matters because a transaction can appear successful before it is final. Faster finality could let a merchant or a bridge relying on a stronger settlement guarantee act sooner, while leaving transaction execution, fees and wallets unchanged, the Foundation says. Alpenglow also removes validator vote transactions from blocks, so reported transaction counts may drop even if user activity stays steady, CoinDesk reported.

What happens on Oct. 21?

The migration starts with epoch 1064, then switches consensus after an initial transition period. CoinDesk reports Solana will keep its old voting system for the first 5,000 slots, with the Alpenglow switch expected about 18 minutes after the epoch begins. The planned date is therefore the start of a staged protocol change, not a claim that every transaction will immediately finalize in 150 milliseconds.

What must validators do before the change?

Solana’s upgrade guidance sets out two steps for validator operators:

  1. Run an Agave-based client built on version 4.3.0. Firedancer and Frankendancer are not supported during the migration.
  2. Keep at least 0.8 SOL above the vote account’s rent-exempt minimum to pay the Validator Admission Ticket fee.

For you as a wallet user, the Foundation says no action is needed: signing and sending transactions will work as before. The change is to how the network reaches finality.

Sources