Newsletter
- According to the Solana Foundation, Alpenglow will be enabled on block epoch of the Solana mainnet, and this epoch is expected to begin around 15:00 on Wednesday, October 21st (UTC).
- This upgrade will replace TowerBFT and reduce the target time for final transaction confirmation to approximately 150 milliseconds, which is lower than the current 12.8 seconds.
- Voting transactions will be removed from the blockchain, so the total number of apparent transactions for Solana and the data for TPS will decrease significantly, but the actual activity will not decrease as a result.
Solana has set October 21st as the launch date for Alpenglow. Alpenglow will fully replace the system currently used by validators to reach consensus. This switch is bound to epoch 1064, and the Solana Foundation expects this process to begin around 15:00 (UTC) on Wednesday.
Alpenglow will phase out the current TowerBFT system in use, and strive to reduce the final confirmation time of transactions to approximately 150 milliseconds. By 'final confirmation', we mean the moment at which a transaction becomes irreversible; under TowerBFT, this process currently takes about 12.8 seconds.
On the current Solana network, a payment is usually confirmed quickly, but this is not a guarantee. Before the 13-second timer on TowerBFT expires, there is still a possibility that the block in question could be discarded.
It is precisely this low-probability uncertainty that makes anyone dealing with real funds typically wait for the entire time window to expire. If the final confirmation time is reduced to about 150 milliseconds, then the irreversible outcome will almost as quickly occur as with an optimistic confirmation, which is exactly what is needed in cashier scenarios that accept SOL payments, DeFi applications, or trading desks that conduct position settlements.
The working mechanism of TowerBFT is for verifiers to publish their votes as on-chain transactions; only when a cumulative total of votes equivalent to 32 slot votes is reached will a block be considered finally confirmed. The voting protocol Votor, which was introduced alongside Alpenglow, moves the votes off the chain. As a result, verifiers will directly communicate with each other, package the votes into certificates, and can lock a block within a maximum of two rounds of voting after one round of voting.
If 80% or more of the staking votes support a particular block in the first round, that block will be finalized on the spot. If the support rate falls between 60% and 80%, it will proceed to a second round, where a threshold of 60% will determine whether the block is finalized or skipped. The foundation stated that this design can tolerate 20% of malicious staking, in addition to another 20% of offline staking.
Anza wrote on X on October 13th: "The time has come. Alpenglow will go live on mainnet-beta at around 14:50 on Wednesday, October 21st (UTC). After 18 months of work, the migration only took place in one slot. The final confirmation time has been reduced from several seconds to about 150 milliseconds. Please be sure to follow us @anza_xyz and count down together for the launch. For more details, see: https :// t.co / MEf26uzCMW"
Ordinary users do not need to perform any operations, and the performance of their wallets and applications should remain the same as it is now. Solana The virtual machines, transaction formats, programs, and fees will not change; for developers, however, the two commitment levels of “confirmed” and “finalized” will become completely consistent.
In addition to the rent-free balance, each voting account is also required to hold an additional amount of 0.8 SOL to cover the cost of new Validator Admission Ticket. This is a fee that is collected from each epoch and is of equal magnitude; after payment, this fee will be destroyed. It will replace the previous voting transaction fee of approximately 1 SOL per epoch that verifiers had to pay under TowerBFT. If a verifier is unable to pay this fee, they will not be able to participate in voting and block production in the next epoch.
The feature switch will be enabled at the start of epoch 1064, but TowerBFT will still continue to be responsible for another 5,000 slots for about 18 minutes. After that, Alpenglow will take over at slot 459,653,000. This is to ensure stability and to prevent any issues during the transition period.
Verifiers approved Alpenglow as early as September 2025, at which time the SIMD-0326 proposal was passed with 98.27% of the votes in favor. In May of this year, Anza's chief economist, Max Resnick, stated that the team was considering activating the mainnet at the end of the third quarter or the beginning of the fourth quarter, so currently everything is progressing according to plan.
What was launched on October 21st is only Votor, which is the first half of Alpenglow. As for Rotor – it will replace Solana in the Turbine system that is used to broadcast block data among verifiers – it will be launched later, and the exact date is still not determined at this time.
