Solana Alpenglow mainnet activates in Epoch 1064 with 150 ms finality target

The Solana Alpenglow consensus upgrade activated on mainnet during Epoch 1064 on October 21, 2026. The change replaced TowerBFT with the Votor voting and finalization protocol, cutting expected transaction finality from roughly 12.8 seconds to about 150 milliseconds.

Solana Alpenglow mainnet activation timing and process

Epoch 1064 started between 13:20 and 14:00 UTC. The feature gate opened at the epoch boundary, but TowerBFT remained active for the first 5,000 slots, about 18 minutes. Votor assumed control at slot 459,653,000 around 14:00–14:02 UTC, according to timing data from Anza and Solana Compass.

The migration followed SIMD-0384. Validators formed an Alpenglow genesis certificate requiring roughly 82 percent of stake. Blocks carried only votes for a brief window of one or two slots, after which user transactions resumed. RPC, WebSocket, and gRPC services stayed available throughout.

Validators must run Agave-based clients version 4.3.2 or later. Firedancer clients were unsupported during the switch. Each validator maintains at least 0.8 SOL above rent-exempt balance in its vote account to cover the Validator Admission Ticket fee, which is burned each epoch.

Technical changes and network effects

Votor moves voting off-chain. Validators send direct messages and aggregate results into compact BLS certificates instead of posting individual vote transactions on-chain. The fast path reaches finality when 80 percent or more stake participates in one round, taking roughly 100 milliseconds. The fallback path uses a 60 percent threshold over two rounds for about 150 milliseconds total.

The upgrade tolerates up to 20 percent malicious stake and another 20 percent offline stake. Confirmed and finalized commitment levels now converge at the same point. Proof-of-History no longer paces block production timing.

Transaction formats, fees, and SVM execution remain unchanged for users and applications. Vote transactions disappear from blocks, which lowers reported TPS figures. Operators can verify the switch with the getAgGenesisCert RPC method or the solana alpenglow-genesis-info CLI command.

Background, prior testing, and next steps

The proposal was first presented in May 2025 at Solana Accelerate. SIMD-0326 governance passed in September 2025 with 98.27 percent approval. Testnet activation occurred on September 24, 2026, and devnet followed on September 25. A separate slot-time reduction to 200 milliseconds and the VAT mechanism were completed earlier in 2026.

Rotor, the planned replacement for Turbine, remains unscheduled. Teams will monitor post-activation finality times, stake distribution effects, and any follow-on client releases such as Agave 4.4. The change supplies sub-second finality that developers can use for new real-time applications while leaving existing wallet and dApp behavior intact.