Solana validators activated the Alpenglow consensus protocol on mainnet-beta on October 21, 2026, replacing TowerBFT at slot 459,653,000, core developer Anza said. Anza said the time for a transaction to become irreversible fell from about 12.8 seconds to roughly 150 milliseconds. That is full finality, not the conditional confirmation Solana already provided within seconds under TowerBFT.
Validators switched protocols while the network was running and carried its existing ledger forward. Other upgrades, including the proposed post-quantum Quantumglow design, have no committed dates.
