# Solana's Alpenglow consensus is scheduled to switch on mainnet on October 21

Canonical page: https://technooptimist.io/stories/solana-s-alpenglow-consensus-is-scheduled-to-switch-on-mainnet-on-3b281ea6
Date: 14 Oct 2026
About: [Solana](https://technooptimist.io/companies/solana.md) · [Alpenglow consensus](https://technooptimist.io/crypto/alpenglow.md)
Original source: https://unchainedcrypto.com/anza-puts-solanas-alpenglow-consensus-switch-on-the-mainnet-calendar-for-oct-21/

Anza has set Wednesday, October 21, 2026 as the date Alpenglow replaces TowerBFT on Solana's mainnet-beta, announced on X this week. Anza says the change cuts finality from about 12.8 seconds to about 150 milliseconds and raises the share of stake the network can tolerate misbehaving.

## Key facts

- The switch happens at a feature-gate epoch boundary, with a 5,000-slot countdown in which blocks carry only validator votes, so they can be rolled back.
- Anza expects the handoff itself to take hundreds of milliseconds, so the switch is not literally instant.
- Fault tolerance rises to 40% of stake offline or misbehaving, versus under 33% adversarial stake for TowerBFT; these are Anza's claims, not independently verified.
- Validator votes move off-chain as BLS-signed messages combined into one certificate, which Anza says frees block space.
- Testing included a bug bounty of over 25,000 SOL, work from 115 security researchers, a 1,500-node simulation and nine at-scale migrations.

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