Solana has begun the migration of Alpenglow to its public testnet, taking the new consensus system to a broader stage of testing before a future activation on the mainnet. The upgrade's main goal is to reduce finality, currently at around 12.8 seconds, to approximately 150 milliseconds.
The change represents a reduction of almost 99% in the time required for a block to be considered irreversible. In practice, finalization could occur more than 80 times faster if the projected performance is confirmed in testing.
Alpenglow replaces the current TowerBFT with the voting protocol Votor. Instead of recording validator votes as transactions and accumulating confirmations over several slots, the new system allows validators to exchange votes directly and reach finalization in one or two rounds. Solana's transaction execution, contracts and fees do not change with the upgrade.
Testnet will measure performance at a larger scale
The migration expands the testing carried out since May in an environment dedicated to Alpenglow. The public testnet allows evaluating the new consensus with a broader set of validators and infrastructure before any adoption on the mainnet.
The first stage requires Agave 4.3, a client developed by Anza. Firedancer and Frankendancer still appear as unsupported for Alpenglow's activation on the testnet.
The process, however, does not yet mean that 150 ms finality is already active or proven on the testnet. Anza's official tracker updated on September 22 still listed SIMD-0326, which introduces the new consensus, as “Pending Testnet Activation”, with no activation epoch published. The 150 ms remain a technical target to be validated.
A finality close to that level would mainly reduce the waiting time for services that need irreversible confirmation, such as exchanges, bridges and payment systems. Each application, however, will still be able to impose its own controls and processing periods.
Solana has not yet confirmed a definitive date to activate Alpenglow on the mainnet. The foundation positions the upgrade within the Agave 4.3 cycle and keeps the deployment on the main network scheduled for after the testing phase.
