Alpenglow
Solana's TowerBFT replacement. Mainnet epoch 1064 on 21 October 2026 (~15:00 UTC), starting at slot 459,653,000. Expected finality ~150ms; slot time is already 200ms. Yellowstone clients must speak proto 14 and key state on (slot, bank_id).
In detail
Alpenglow is Solana's next consensus protocol. Votor ships in Agave 4.3 and activates on mainnet at epoch 1064, Wednesday 21 October 2026 around 15:00 UTC (Anza quoted ~14:50 UTC), beginning at slot 459,653,000. Feature gate A1pengvuM6JEcyNuTnMqepBKhwHE3N6PmUrdATGawhJS. Expected finality compresses from ~12.8s under TowerBFT to ~150ms; that is an expectation, not a constant, and it is not the same thing as slot time (already 200ms from epoch 1053). For Yellowstone gRPC the breaking work is bank_id: a slot can have multiple candidate banks, reconstruction must key on (slot, bank_id), subscribe() no longer reconnects (use subscribe_with_reconnect and handle DiscardBanks), vote transactions leave the block, and confirmed/finalized converge. Subglow is Alpenglow-ready on Yellowstone gRPC. JSON-RPC is unchanged.
Key points
- Mainnet epoch 1064, 21 October 2026 ~15:00 UTC, slot 459,653,000
- ~150ms is expected finality, not slot time (already 200ms)
- Key Yellowstone state on (slot, bank_id), never slot alone
- subscribe() no longer reconnects — use subscribe_with_reconnect
- Subglow is Alpenglow-ready; JSON-RPC does not change