Solana schedules Alpenglow upgrade for October 21

The Solana Foundation plans to activate Alpenglow at epoch 1064 on October 21, 2026. The upgrade replaces TowerBFT with Votor and targets transaction finality of about 150 milliseconds, compared with roughly 12.8 seconds currently. Validators will need an Agave 4.3.0-based client and at least 0.8 SOL in their vote account.

Alpenglow’s activation is tied to epoch 1064, expected to begin around 15:00 UTC on October 21, 2026. The switch should occur at slot 459,653,000, after the epoch’s first 5,000 slots. The redesign swaps TowerBFT for Votor: validators exchange votes directly and bundle them into certificates, allowing finality after one or two voting rounds instead of waiting for 32 slots of vote transactions.

The projected 150 ms applies to finality, not block production, and fees, programs, and transaction formats remain unchanged. Wallets and apps are expected to keep working without user action. Validators face a breaking change: they need an Agave 4.3.0-based client, while Firedancer and Frankendancer are unsupported during transition, and each voting validator must maintain at least 0.8 SOL in its vote account.

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