Solana Sets Oct. 21 Date for Alpenglow Upgrade

Solana core developer Anza announced Oct. 13 that the Alpenglow upgrade will begin its mainnet activation on Oct. 21. The upgrade targets a reduction in transaction finality from about 12.8 seconds to 150 milliseconds, or nearly 99%.\n\nThe migration is scheduled to start at about 15:00 UTC, when epoch 1064 begins. Solana will continue using its current TowerBFT consensus system for another 5,000 slots, or about 18 minutes, before attempting to switch to Alpenglow’s Votor system.\n\nThe upgrade is designed to reduce the time between processing a transaction and treating it as irreversible. Solana recently reduced block-production times to about 200 milliseconds, which affects transaction processing speed. Alpenglow addresses the separate delay required for network-wide confirmation.\n\nTowerBFT records validator votes as blockchain transactions, with agreement building across several blocks. Votor will allow validators to exchange votes directly and combine them into cryptographic certificates. Blocks could then become final after one or two voting rounds.\n\nThe Solana Foundation has linked faster finality to payment providers, trading platforms and applications using tokenized assets or stablecoins. Payment companies could treat transfers as settled sooner, while platforms that require confirmed transactions could complete follow-up operations more quickly.\n\nThe 150-millisecond figure is a target, not a confirmed mainnet result. Finality times will depend on network conditions, validator participation and the number of voting rounds required.\n\nThe migration requires validators representing at least 82% of staked SOL to sign a genesis certificate, which will establish Votor’s starting point. User transactions will briefly stop being included in blocks during the handover. Normal processing is expected to resume after the new consensus system takes control.\n\nValidator operators must use software based on Agave 4.3.0 for the migration. Firedancer and Frankendancer clients will not be supported during the transition. Validators must also hold at least 0.8 SOL above their rent-exempt balance to pay a new participation fee. Validators that do not meet the requirement will be excluded from voting and block production in the following epoch.\n\nAlpenglow has been deployed on Solana’s testnet and devnet, where developers have tested the planned changes. The Oct. 21 migration will be the first test of the replacement of TowerBFT on Solana’s live network while it remains operational.\n\nTransaction execution will not change, so existing applications are expected to continue running without changes to their underlying programs. Removing validator votes from blockchain transactions could create more capacity for user activity and may reduce the transaction counts reported by the network.\n\nA separate Alpenglow component called Rotor, which is designed to change how blocks are distributed across Solana, is scheduled for a later release.