Solana Alpenglow Test Cluster Completes Migration Before Oct. 21 Switch

Solana’s Alpenglow community test cluster completed a consensus migration and recorded six resets, a failed migration and a rollback as validators prepared for the planned Oct. 21 mainnet handoff.

Galaxy has operated a validator on the cluster since June. During that period, the cluster was reset six times from fresh genesis blocks. It also underwent a failed migration, a rollback and a successful migration. Those events involved the test cluster, rather than changes carried out by Galaxy alone.

On mainnet, the Alpenglow consensus upgrade begins with a feature gate at the start of epoch 1064, estimated for about 9:20 a.m. ET (13:20 UTC) on Oct. 21. TowerBFT is expected to remain active for roughly 5,000 more slots, or about 18 minutes, before Alpenglow takes over at slot 459,653,000. The clock time can shift with the network’s slot rate.

Alpenglow changes how validators determine that a block is final. Instead of placing individual vote transactions on the chain, validators exchange votes directly and combine signatures into certificates. A block can become final after one voting round with support from 80% of stake. A second-round path uses 60% stake thresholds.

The protocol targets finality of about 150 milliseconds under normal network conditions. That remains a target, rather than a measured mainnet result, and nodes outside the admitted validator set may learn of finalization later. Solana’s separate move to a 200-millisecond target slot time on Oct. 9 changed how often blocks are produced; Alpenglow targets the time it takes transactions to become final.

Operators need an Agave-based v4.3.2 client for the migration. Firedancer and Frankendancer are unsupported during the handoff. Validators must also keep at least 0.8 Solana (SOL) in their vote accounts above the required reserve. The admission charge is 0.8 SOL per epoch at the current slot setting. The first charge comes at the start of epoch 1064 and covers participation in epoch 1065.

This first phase, Votor, changes voting and finalization. A later phase, Rotor, is planned to change how blocks spread across the network. The next step is the epoch 1064 feature gate on Oct. 21, followed by the scheduled consensus handoff about 5,000 slots later.