Solana has begun testing the Alpenglow upgrade on its established testnet, aiming to reduce transaction finality from 12.8 seconds to just 150 milliseconds. The upgrade requires no changes for end users or wallets, allowing applications to continue executing transactions as usual while significantly improving network speed. Validators participating in the test must run Agave 4.3, the primary Solana client software maintained by Anza. While alternative validator clients exist to reduce single-software dependency risks, this initial migration will rely entirely on Agave. Anza has tentatively scheduled mainnet feature activation for Sept. 28, though the official Alpenglow launch date remains unconfirmed as the testnet transition is still pending.