Solana sets Alpenglow mainnet launch for Oct. 21, cutting finality from 12.8 seconds to 150 milliseconds

Solana will replace the consensus mechanism it has run since launch on the night of Oct. 21. Anza, Solana's core development firm, said on its official X account on Oct. 13 that the new consensus protocol Alpenglow will go live on mainnet at around 2:50 p.m. UTC on Oct. 21, or about 11:50 p.m. KST. The Solana Foundation also said on its upgrade page that the feature will activate at the start of epoch 1064 (an epoch is a defined period in the network's validator schedule), which begins on Oct. 21.

"Finality drops from seconds to ~150ms," Anza said. According to the foundation, transactions currently take about 12.8 seconds to reach final confirmation under TowerBFT, the existing consensus mechanism.

Thirteen months from vote to mainnet

Alpenglow was adopted through a validator vote last September. The Solana Improvement Document SIMD-0326 passed on Sept. 2, 2025, with 98.27% of participating stake voting in favor. The required features have since been switched on one by one, and two test networks have already completed the transition.

The two organizations give slightly different times. Anza wrote "~14:50 UTC," while the foundation said "approximately 15:00 UTC." For the first 5,000 slots (about 18 minutes) after activation, TowerBFT keeps running, and the network then switches to the new mechanism using one block as its reference point (genesis). Anza expects the handoff to take hundreds of milliseconds.

Votes move out of blocks

Validator votes are currently recorded inside blocks like transactions. Under Alpenglow, votes become signed messages that validators send directly to one another, and they are bundled into a single certificate. Votor, the voting component, finalizes a block in one round if at least 80% of stake supports it, or in two rounds with at least 60%. The foundation said the network can withstand 20% malicious stake and 20% offline stake at the same time.

Anza said it has offered a bug bounty of more than 25,000 SOL, drawn 115 security researchers and run simulations at the scale of 1,500 nodes. It added that nine full-scale migration tests have succeeded.

Nothing for users to do, 0.8 SOL more for validators

The foundation said users do not need to take any action. Transaction signing and sending, fees and the smart contract execution environment stay the same. However, because votes leave blocks, reported transaction counts and transactions per second (TPS) will fall. This reflects a change in how activity is counted rather than an actual drop in activity, and the foundation advised dashboard operators to re-baseline their figures.

Validators must switch to a client based on Agave 4.3.0 (Agave, Jito-Solana or Harmonic Salsa) before epoch 1064 begins on Oct. 21. Firedancer and Frankendancer are not supported during the migration. Vote accounts must hold an extra 0.8 SOL on top of the minimum balance. That amount is burned each epoch as the admission ticket fee, and validators that cannot pay it are excluded from voting and block production in the next epoch and lose that epoch's rewards.

SOL at 141,800 won on Upbit, no deposit notice yet

SOL traded at 141,800 won on Upbit's Korean won market at 7:31 a.m. KST on Oct. 15, down 1.9% from the previous day. At the same time, it was at $104.58 on Binance, down 2.2% over 24 hours. The kimchi premium (the gap between prices on Korean exchanges and global markets) on Upbit was about 1.1%. The funding rate on Binance's SOL perpetual futures was 0.008%, meaning long positions were paying a small fee.

Korean exchanges often suspend deposits and withdrawals of a coin briefly during network upgrades. As of the morning of Oct. 15, Upbit had not posted a notice on SOL deposit and withdrawal schedules related to Alpenglow.