Solana Begins Testing Alpenglow Upgrade to Slash Finality to 150ms

Solana Alpenglow upgrade — Solana developers have begun testing a major network upgrade, dubbed Alpenglow, which aims to drastically reduce transaction finality times from over 12 seconds to just 150 milliseconds.

The upgrade, now live on a public testnet, replaces Solana’s current TowerBFT consensus system with a new mechanism called Votor. This change allows validators to finalize blocks after just one or two rounds of direct voting, potentially making payments irreversible almost instantly without altering how users send funds.

For exchanges, bridges, and merchants, faster finality means they could treat incoming Solana payments as settled much sooner, improving the user experience for deposits and cross-chain transactions. The initial testnet phase requires validators to run the Agave 4.3 client software.

A tentative mainnet update is scheduled for September 28, though developers have clarified this is not a confirmed launch date for Alpenglow. The current testnet does not yet support Solana’s new Firedancer or Frankendancer validator clients.