Solana’s 150-millisecond settlement upgrade reaches second public test network

Solana’s planned protocol upgrade, Alpenglow, is now active on the blockchain project’s public developer network (devnet) and on its separate testnet, giving application teams and node operators places to test software before any change is applied to the live mainnet. Anza, the company that produces Solana’s core software, announced the devnet transition on Sept. 25; the testnet completed its switch a day earlier. The Solana Foundation’s upgrade page shows Alpenglow as active on both networks.

Alpenglow aims to shorten finality — the point at which a transaction cannot be reversed — to roughly 150 milliseconds, compared with about 12.8 seconds under Solana’s current mechanism. That target is based on simulations rather than demonstrated performance under live-market conditions, and the Foundation noted additional delays can come from wallet processing or exchanges’ deposit checks.

The upgrade changes how validators reach agreement. Instead of recording validator votes as transactions inside blocks, validators will exchange votes directly and reach consensus in one or two voting rounds. Because votes will no longer be recorded as transactions, some metrics and activity charts that counted those votes will report lower transaction totals even if user activity stays the same; the Foundation has urged data providers to adjust their comparisons.

Service operators that build transaction histories or index blockchain state must also adapt: they need to keep competing candidate blocks separate until the network finalizes a single block, otherwise merging contents could produce incorrect records. By contrast, the Foundation’s guide says applications that only send transactions and read account balances do not require migration.

No firm date has been set for Alpenglow’s mainnet launch. Anza’s software schedule allows for feature activations to resume on Sept. 28, 2026, but it does not identify that date as the upgrade’s activation on mainnet. The Foundation and Anza have limited the rollout so far to test networks while performance in live conditions remains to be demonstrated.