Solana Activates Alpenglow, Targeting 150ms Finality

Solana's Alpenglow consensus upgrade is live on mainnet. The Solana Foundation says it activated in epoch 1064, which started on Wednesday 21 October at about 13:36 UTC.

The headline number is finality, the point at which a transaction cannot be reversed. Under TowerBFT, the previous model, that took about 12.8 seconds. Alpenglow targets roughly 150 milliseconds.

The Foundation's Alpenglow dashboard, read on 21 and 22 October, showed a latest observed finality of 202ms. That is a single reading, not a sustained average, so the 150ms target has not yet been shown to hold on mainnet.

Votor Replaces the Old Voting Process

The part that shipped is Votor, the first phase of Alpenglow, delivered in Agave 4.3. Validators now send votes directly to each other and bundle them into certificates. A block is final after one or two rounds of voting.

The handover is recorded on chain. Slot 459,652,999 served as the Alpenglow genesis block, certified with votes from 446 of the network's 654 validators. Alpenglow consensus runs from slot 459,653,000. The dashboard later showed 449 certificate signers.

The mainnet switch followed a devnet activation at 19:30 UTC on 25 September. We covered the run-up to the mainnet activation on the day.

Why Solana TPS Charts Just Fell

Anyone tracking Solana throughput will see a sharp drop in transactions per second. The Foundation says this is an accounting change: vote transactions are no longer included in blocks, so the count fell without any drop in real activity.

That makes TPS figures from before and after 21 October hard to compare directly. Any chart that spans the switch mixes two different measures.

The 150ms figure is also easy to misread. It is finality, not block time. Block time was cut separately, with slot times reduced from 400ms to 200ms in four stages that completed in October 2026.

What Changes for Validators and Users

For users, nothing does. The Foundation says signing, sending and approving a transaction work as before, and wallets and applications need no changes. Execution is untouched: the Solana Virtual Machine, transactions, programs and fees stay the same.

Validators carried the load. To take part they had to run an Agave-based client at v4.3.2:

• Agave
• Jito-Solana
• Harmonic Salsa

Firedancer and Frankendancer were not supported for the migration. Validators must also hold at least 0.8 SOL in their vote account, above its rent-exempt minimum. That balance pays the Validator Admission Ticket fee.

What to Watch Next: Rotor

Alpenglow is not finished. Its second phase, Rotor, is a new protocol for distributing block data and is intended to replace Turbine. The Foundation says it is planned for a later release now that Votor is live, and it is not yet scheduled.

Two details remain open. Activation timing differs across accounts: the Foundation gives the epoch start at about 13:36 UTC, while a later time has been cited from the dashboard, possibly marking the first block finalised under Alpenglow. No source explains the gap.

The more useful test is the dashboard itself. If observed finality settles near 150ms over the coming days, the upgrade is delivering its target. Readings that stay well above that, like the 202ms print, would show Votor running but short of the figure Solana set for it.