Solana replaced its consensus protocol while it kept running

On 21 October 2026, at the start of epoch 1064, Solana mainnet switched from TowerBFT to Alpenglow, a consensus protocol built by Anza. The cluster ran the old protocol for 5,000 more slots, about 18 minutes, then waited for enough stake to sign a genesis certificate before user transactions resumed under the new rules. That certificate, anchored at slot 459,652,999, can be read from any public mainnet RPC.

The headline change is finality, from roughly 12.8 seconds to a target of about 150 milliseconds. The quieter changes matter as much. The design tolerates 20% of stake acting maliciously plus another 20% offline, and it replaces per-vote transaction fees of about 1 SOL per epoch with a flat admission fee of 0.8 SOL per epoch, which is burned.

For a payment that has to be final before a shopkeeper hands over goods, or before a remittance agent releases cash, thirteen seconds against a fraction of one is the difference between waiting and not. Shared public infrastructure becoming faster and more fault tolerant, in the open, belongs on this page.