Solana activates Alpenglow finality upgrade on public testnet

Solana has activated Alpenglow on its public testnet, starting broader validator testing of a consensus change that targets finality in about 150 milliseconds, down from roughly 12.8 seconds. The Solana Foundation’s Alpenglow upgrade page lists the testnet feature gate as active and the devnet and mainnet gates as not activated.

CoinDesk reported on Sept. 23 that Alpenglow had moved to the public test network. The target is a planned reduction: the Foundation says the upgrade is still in development, and the 150-millisecond figure describes its expected finality time, not a result established on mainnet.

How does Alpenglow aim to reach finality faster?

Alpenglow replaces Solana’s TowerBFT consensus layer with Votor, the Foundation says. Under TowerBFT, validators vote through transactions recorded on-chain, and enough votes accumulate across 32 slots before a block becomes final. Votor instead has validators send votes directly to one another and combine them into certificates.

The Foundation says Votor can finalize a block after one or two rounds of voting. That shortens the consensus process; it does not change how Solana executes transactions. The Foundation says the SVM, programs, transactions and fees remain unchanged.

What is being tested on the public network?

The testnet activation lets validators and developers try the new consensus system with the broader set of computers and services that run Solana’s test network. CoinDesk reported that Alpenglow had already run for more than four months on a separate community cluster, where the migration process could be rehearsed.

The Foundation’s status page identifies Votor as the first rollout phase, included in Agave 4.3. It says Rotor, a planned replacement for the block-propagation system Turbine, is a later phase and has no scheduled release.

When could Alpenglow reach Solana’s mainnet?

It has not activated there. The Foundation’s page lists the mainnet feature gate as inactive, and its rollout instructions say each cluster activates on its own schedule. CoinDesk also reported that a Sept. 28 mainnet software update was tentative and was not a confirmed Alpenglow launch date.

For applications that wait for finality before treating a transaction as irreversible, the target could shorten settlement waits. CoinDesk cited exchanges, bridges and merchants as services that rely on finality. Whether Alpenglow delivers the target across Solana’s main network remains to be shown after testing and later activation.