Solana is about to swap out the engine of its consensus system. A readiness snapshot shared on X flagged 151 Solana validators, holding 20.3% of the network’s stake, as unprepared for the Alpenglow upgrade. Alpenglow is expected to activate on October 21, 2026, at approximately 13:20 UTC. The snapshot was taken on October 20, one day before the switch.
What validators need before the switch
Validators who want to keep voting on blocks need three things in order.
First, they must run an Agave-based client at version 4.3.2. Agave is the validator software that most of the network runs. Older versions won’t satisfy the new rules.
Second, each validator needs a registered BLS public key. BLS is a cryptographic signature scheme that lets many individual signatures be combined into one compact proof. Under Alpenglow, those signatures get aggregated off-chain into what the design calls certificates.
Third, every validator must keep at least 0.8 SOL in its vote account. That balance covers a new flat fee tied to the Validator Admission Ticket, or VAT, model.
Per the research findings, most of the 151 flagged validators fell short for fairly mundane reasons. The main culprits were outdated client versions or vote accounts with too little SOL.
Why Alpenglow is a big deal for Solana
The headline feature is speed. The new voting component, called Votor, aims to cut finality from roughly 12.8 seconds to about 150 milliseconds.
Alpenglow also retires TowerBFT, the voting mechanism Solana has used to reach agreement on the state of the chain. In its place comes an architecture where votes are bundled as aggregated BLS signatures instead of being processed one by one.
The upgrade also caps the active validator set at 2,000, ranked by stake weight.
Community support for the overhaul was close to unanimous. The proposal passed with 98.27% approval in September 2025. Testing then ran across various network environments throughout 2026.
Only the first phase goes live in October. That covers Votor plus the VAT and BLS requirements. Further enhancements are slated for later stages.
Readiness has improved, but the gap remains
The 20.3% figure actually reflects progress. Earlier readiness trackers showed about 45% of stake, roughly 198 million SOL, failing to meet all the criteria ahead of the upgrade.
Stake matters more than headcount here. Solana’s voting power is weighted by how much SOL is delegated to each validator. So 151 validators holding 20.3% of stake carry far more weight than their raw number suggests.
What this means for SOL holders and the network
For validators, the stakes are straightforward. Operators who miss the requirements could find themselves unable to participate in voting once the new rules take effect. Everyone delegating SOL to those validators would be exposed to that outcome as well.
Stakers may want to check whether their chosen validator is running Agave 4.3.2 and has its BLS key registered.
Disclosure: This article was edited by Estefano Gomez. For more information on how we create and review content, see our Editorial Policy.