Solana activates Alpenglow consensus on testnet and devnet
Solana has switched on its Alpenglow upgrade on two public test networks, replacing TowerBFT with Votor and targeting finality of 100 to 150 milliseconds, though mainnet timing is unset.
Key points
- Alpenglow went live on testnet on 24 September and devnet on 25 September, replacing TowerBFT with the Votor consensus mechanism.
- The design targets finality of 100 to 150 milliseconds, down from roughly 12.8 seconds for economic finality today.
- The testnet transition completed at slot 444,625,255 after a 5,000-slot countdown of about 17 minutes; devnet finished at slot 504,148,999.
- SIMD-0326 won governance approval in September 2025 with 98.27% of participating votes, and a community cluster has rehearsed the change since May.
- Firedancer and Frankendancer still need Votor support, and Anza has not announced a mainnet launch date.
Solana has activated its Alpenglow consensus overhaul on two public test networks, according to Bitcoin.com News. Anza, the team behind the Agave validator client, switched the upgrade on for testnet on 24 September and for devnet on 25 September. The change replaces the network's long-standing TowerBFT system with a new mechanism called Votor.
The headline promise of Alpenglow is speed. The design targets transaction finality of 100 to 150 milliseconds, compared with roughly 12.8 seconds for economic finality on Solana today. Co-founder Anatoly Yakovenko marked the devnet countdown with a short message: "You are not ready for this."
The testnet transition followed a 5,000-slot countdown lasting about 17 minutes and finished at slot 444,625,255. The final TowerBFT block carried 82% of stake, after which an Alpenglow genesis block retired the old system on that cluster. Devnet completed its own switch at slot 504,148,999. A dedicated community cluster had rehearsed the change since May, including an early attempt that failed and needed a restart.
Alpenglow goes live on testnets
Under the existing system, validators submit votes as onchain transactions and wait through a 32-slot confirmation chain. Those voting transactions reportedly make up about 75% of network transaction counts. Votor moves voting offchain, gathering peer-to-peer votes into compact BLS certificates. Two confirmation paths run at once: a fast path where 80% of stake agrees in one round, targeting 100 milliseconds, and a fallback where 60% agrees first and a second round follows, targeting 150 milliseconds.
The trade-off is a revised security model that accommodates 20% adversarial stake and a further 20% offline. Rotor, the planned replacement for Turbine block propagation, will come later. The Solana Virtual Machine, transaction format, programs and fees are unchanged, and wallet users will not need to migrate anything.
Faster settlement brings practical complications. Exchanges, bridges and custodians may still process deposits using systems built around longer confirmation periods. Removing validator votes from blocks will also push reported transaction counts down even if user activity is unchanged. Anza has warned infrastructure providers to prepare: indexers must tell competing candidate banks apart until final certification, and Geyser and gRPC consumers get a new bank_id identifier.
Votor replaces onchain voting
The advertised performance comes from simulations and smaller-scale testing, and sustained results across a full public validator set remain unproven. Firedancer and Frankendancer have not implemented Votor, so the first public transitions depend on Agave 4.3. Anza wants developers testing integrations during an observation period before any mainnet-beta migration, and no firm activation date has been announced. A 28 September window in Agave schedules covers resuming feature activations, not a confirmed Alpenglow launch.