The Solana network has deployed the Alpenglow upgrade to its public testnet, achieving a median block finalization time of 54 milliseconds. This result significantly outperforms the initial design target of 100–150 milliseconds and marks a major improvement over the current mainnet average of approximately 12.8 seconds.
Central to the update is the Votor consensus mechanism, which replaces the long-standing TowerBFT system. Votor shifts voting off-chain, allowing validators to exchange BLS-signed votes via a peer-to-peer network. This approach aggregates signatures into compact certificates, reducing the block space previously consumed by on-chain vote transactions.
The upgrade also implements dual finalization paths and a 20+20 fault-tolerance model to enhance network performance and resilience. Notably, the Solana Virtual Machine, transaction formats, and fee structures remain unchanged. The proposal, designated SIMD-0326, received 98.27% approval from validators in September 2025.
Alpenglow launched on the public testnet on September 24, 2026, at slot 444,625,255, followed by a devnet release on September 25 at slot 504,148,999. Mainnet deployment is scheduled alongside the Agave 4.3 release, expected in late September or October 2026, pending final observations from the test environments.
