Solana activates Alpenglow, targeting 150ms finality

Solana activated its Alpenglow consensus upgrade on Oct. 21, replacing the system it had used since 2020 and aiming to make transactions final in about 150 milliseconds. The CoinDesk report on the change says the new system changes how validators vote and certify blocks. Finality is the point when an app can treat a payment as settled.

How do validators make a block final?

Under the old TowerBFT system, validators recorded votes as blockchain transactions and approvals built up across successive blocks. Alpenglow removes those vote transactions. Validators send votes directly to one another, and the network combines approvals into certificates. A block can then become final after one or two rounds of voting.

As Decrypt reported, citing core developer Anza, validators switched at slot 459,653,000, carrying the existing ledger forward. Decrypt says the earlier system took about 12.8 seconds to reach full finality; Alpenglow targets roughly 150 milliseconds. CoinDesk reported that votes from 446 of 654 participating validators certified the block used to start the new system. The handover took about 900 milliseconds, according to the Solana Foundation.

The certificate works like a signed receipt: it gives the network a shared record that the block has been approved. The key change is that validators exchange those approvals directly instead of writing them into later blocks.

What could users notice in payments and deposits?

Apps can use finality to decide when to release funds or goods. CoinDesk says some Solana apps already showed transactions as confirmed before they had reached full finality, leaving an additional wait for settlement. With Alpenglow, an exchange could credit a deposit sooner, or a shop could treat a stablecoin payment as settled sooner.

The 150-millisecond figure is a target under normal network conditions, not a guarantee for every payment. How quickly finality appears in an app also depends on the service receiving the information; some computers may get it later than validators voting directly.

Do users need a new wallet, and will transaction counts change?

No wallet change is required, and CoinDesk reports that fees and how applications run remain unchanged. But dashboards may show fewer total transactions because validator votes no longer appear on-chain as transactions. A lower count may reflect the removed vote records, not fewer user payments or trades.

For users, the upgrade changes the wait for a transaction to become settled. The wallet remains the same; the validators reach that shared decision through a new voting path.

Source material

• CoinDesk report on the change — coindesk.com
• Decrypt reported, citing core developer Anza — decrypt.co