Solana Alpenglow Upgrade Set for Oct 21, Finality Drops to 150ms
The Solana Foundation says the switch begins in epoch 1064 around 15:00 UTC on Wednesday, October 21. Votes move off-chain, so headline transaction counts will fall sharply without real activity dropping.
Solana's Alpenglow upgrade goes live October 21, replacing TowerBFT and targeting 150-millisecond finality. Vote transactions move off-chain, so reported transactions per second will drop sharply even though actual network use stays the same.
Solana has picked a date. The Alpenglow upgrade lands on mainnet in epoch 1064, which the Solana Foundation says starts around 15:00 UTC on Wednesday, October 21. That's when TowerBFT, the system validators use to agree on the ledger, gets retired.
Under TowerBFT, a transaction isn't truly final until about 12.8 seconds pass. That's the moment it becomes irreversible, not just optimistically confirmed. Alpenglow's new voting protocol, Votor, targets roughly 150 milliseconds. Validators vote off-chain, package votes into certificates, and can lock a block after one voting round if at least 80% of stake backs it. If support lands between 60% and 80%, a second round decides. The design tolerates 20% malicious stake plus another 20% offline, according to the Foundation.
Why the transaction count drop is not a slowdown
Right now, validators post votes as on-chain transactions. Those votes leave blocks under Votor. So Solana's headline transaction counts will fall sharply, but that's not a drop in real user activity. It's just cleaner bookkeeping. Ordinary users don't need to do anything. The Solana Virtual Machine, transaction formats, programs, and fees stay the same. For developers, "confirmed" and "finalized" commitment levels become one and the same.
Validators already approved the change way back in September 2025, with 98.27% of votes in favor on SIMD-0326. Anza's lead economist Max Resnick told Decrypt in May that late Q3 or early Q4 activation was the plan, so this is on schedule.
There's a catch worth knowing: each vote account needs 0.8 SOL on top of its rent-exempt balance to pay a new per-epoch Validator Admission Ticket. That ticket gets burned. It replaces roughly 1 SOL per epoch in old vote transaction fees. A validator that can't cover it sits out voting and block production for the following epoch.
The takeaway
Solana is about to get much faster to finality, but its headline transaction counts will look smaller. Don't confuse the two.
Summary written by Oh Cannot from the original report by Decrypt. Not financial advice.
