Solana has begun testing its highly anticipated Alpenglow upgrade on the public testnet, a consensus change designed to reduce transaction finality from roughly 13 seconds to about 0.15 seconds. Finality marks the point at which a transaction becomes irreversible, and faster finality could improve exchange deposit crediting, cross-chain bridge releases, and payment confirmations.
Currently, Solana uses TowerBFT, where validators place votes on-chain and build support across 32 slots before a block is finalized. Alpenglow replaces that process with Votor, a voting protocol in which validators send votes directly to each other and can reach agreement in one or two voting rounds. The upgrade is designed to change consensus without altering normal transaction execution, meaning wallet users and applications should not need to change how they send funds or process transactions.
Before moving to the public testnet, Alpenglow ran for more than four months on a smaller network. The public testnet phase will let developers check migration steps, identify faults, and restart the network without risking user funds. Validators participating in the test need to run Agave 4.3, the main Solana software maintained by Anza. Anza recommended Agave 4.3 for mainnet use on Sept. 21 after a staged rollout among validators controlling first 10% and then 25% of staked SOL.
Firedancer and Frankendancer, the alternative validator clients developed by Jump Crypto, do not yet support the Alpenglow test, so the first migration will rely entirely on Agave. Anza lists Sept. 28 as a tentative date for enabling Agave 4.3 features on mainnet, but that does not confirm a mainnet launch date for Alpenglow. Solana has continued making other network changes while preparing the upgrade.
SOL reached a seven-month high above $110 during the week, hitting $117.23 on Sept. 21, although the price move remained separate from the technical testing process. Earlier in the week, SOL recovered above $100 as traders watched key support levels amid broader crypto market moves.
