Solana Activates Its Biggest-Ever Alpenglow Upgrade 🔹 The Solana blockchain activated its Alpenglow consensus protocol upgrade on mainnet on October 21, 2026. 🔹 The upgrade completely replaces TowerBFT, the consensus protocol Solana has used since its launch. It enables validators to agree on transaction ordering and determine when a block is considered final and cannot be reversed. 🔹 On October 13, the Anza team announced that Alpenglow would launch on October 21. The upgrade is the result of Anza's extensive work to change the blockchain's underlying state-consensus mechanism. At the time, developers described the scale of the work as follows: “18 months of work for a migration […] in a single slot.”