Solana
Solana has begun testing its planned Alpenglow upgrade on the network’s public testnet, with developers targeting a reduction in transaction finality from about 12.8 seconds to as little as 150 milliseconds. Finality is the point at which a transaction becomes irreversible, making it particularly important for exchanges, bridges and merchants that need confirmation before completing transfers or payments.
Alpenglow is designed to replace Solana’s existing TowerBFT consensus system with a new voting protocol called Votor. Under the current system, validators record votes on-chain and accumulate enough votes across 32 slots before a block becomes final. Votor instead allows validators to send votes directly to one another and potentially settle on a block after one or two rounds, removing the longer sequence of on-chain votes.
The upgrade is being introduced first on Solana’s public testnet, where developers can test the migration across a broader group of computers and services without putting user funds at risk. Alpenglow has already spent more than four months running on a smaller network created specifically for testing the upgrade.
Validators participating in the test need Agave 4.3, the main software used to operate Solana validators and maintained by Anza. Anza recommended Agave 4.3 to mainnet validators on September 21 after initially deploying it to operators representing 10% and then 25% of the SOL securing the network.
The staged rollout is also intended to reduce Solana’s reliance on a single validator software implementation, although the initial Alpenglow testnet migration will run entirely through Agave. Anza’s schedule lists September 28 as a tentative date for enabling features included in Agave 4.3 on mainnet, but that date is not a confirmed Alpenglow launch date. The testnet activation itself was still listed as pending in Anza’s tracker at the time of the source report.
If testing proceeds successfully, the proposed reduction in finality could materially change how quickly applications can treat Solana transactions as irreversible. For now, however, the 150-millisecond target remains a planned outcome of the upgrade rather than a confirmed mainnet capability.
