Solana has moved its Alpenglow upgrade to a public testnet as developers work toward reducing transaction finality from roughly 13 seconds to just 150 milliseconds.
If successful, the upgrade could allow exchanges, bridges and merchants to recognize transactions as irreversible almost immediately.
Finality refers to the point at which a blockchain transaction can no longer be reversed. Exchanges generally wait for finality before crediting deposits, bridges use it before releasing assets on another network, and merchants rely on it to confirm that received payments cannot be undone.
Alpenglow is now being tested on Solana’s public test network, which mirrors the blockchain while using tokens with no monetary value. This gives developers a way to test the migration, identify technical issues and restart the network without exposing real user funds.
Solana currently relies on TowerBFT to reach consensus, allowing validators to agree on the transactions that will become part of the blockchain’s permanent record. Validators publish votes onchain and accumulate enough support across 32 slots before a block becomes final.
Alpenglow would replace TowerBFT with a new consensus voting mechanism known as Votor. Instead of recording a long sequence of votes on the blockchain, validators would communicate directly with one another and could finalize blocks after one or two rounds.
The upgrade is designed to operate without changing the user experience. Applications can continue processing transactions as they do now, while users would not need to replace their wallets or alter the way they transfer funds.
Before reaching Solana’s public testnet, Alpenglow had spent more than four months operating on a smaller network created specifically to test the upgrade. The broader test will show whether the larger collection of machines and services supporting Solana can transition together.
Validators involved in the test must run Agave 4.3, the main software client used to operate Solana. Anza, one of the network’s development companies, maintains the Agave client.
Anza recommended Agave 4.3 for mainnet validators on Sept. 21 after gradually deploying it to operators representing 10% and then 25% of the SOL securing the network.
Firedancer and Frankendancer, alternative validator clients developed by Jump Crypto, do not currently support the Alpenglow test.
Those clients are intended to diversify Solana’s validator software and reduce the possibility that a single Agave-related problem could affect the entire network. Their absence from the current test means the initial Alpenglow migration will be conducted entirely using Agave.
Anza’s schedule currently lists Sept. 28 as a tentative date for enabling the features included in Agave 4.3 on Solana’s mainnet. However, that date is not a confirmed Alpenglow launch date. Anza’s tracker still showed the public testnet activation as pending as of early Wednesday.
