Solana Schedules Alpenglow Upgrade for Oct. 21 With 150-Millisecond Target

Solana’s mainnet is scheduled to switch to the Alpenglow consensus upgrade on Oct. 21, targeting finality in about 150 milliseconds, down from roughly 12.8 seconds.

The upgrade gate is tied to epoch 1064, now estimated to begin at 9:20 a.m. ET (13:20 UTC). That estimate can move as the network advances. Alpenglow consensus is expected to take over about 5,000 slots later, roughly 18 minutes after the epoch begins.

Validators must run compatible Agave 4.3.2 software and keep at least 0.8 SOL above the rent-exempt minimum in their vote accounts before the epoch starts. That balance covers an admission fee for the following epoch. Applications that index block data need to adjust for changes to streaming data and for validator votes no longer appearing in transaction counts.

The handoff may briefly pause new transaction inclusion in blocks and interrupt some data streams. The 150-millisecond figure is a finality target, not a promised wallet response time.

Alpenglow’s Votor protocol lets validators exchange votes directly and finalize blocks with certificates. The upgrade changes when a transaction becomes irreversible; it does not change transaction execution or user fees.