Solana Validators Holding 20.3% of Stake Flagged as Unprepared for Alpenglow

Solana is preparing to replace the engine of its consensus system with Alpenglow, an upgrade expected to activate on October 21, 2026, at approximately 13:20 UTC. A readiness snapshot shared on October 20 flagged 151 validators, representing 20.3% of the network’s stake, as unprepared for the change.

What Validators Need Before Activation

Validators that want to continue voting on blocks must satisfy three requirements before the switch:

• Run an Agave-based validator client at version 4.3.2. Older versions do not meet Alpenglow’s new rules.
• Register a BLS public key, enabling individual signatures to be combined into compact proofs known as certificates.
• Maintain at least 0.8 SOL in the vote account to cover a new flat fee associated with the Validator Admission Ticket, or VAT, model.

According to the research, most of the flagged validators were short on basic operational requirements rather than facing a deeper technical obstacle. Outdated client versions and vote accounts with insufficient SOL were the primary issues identified.

The stake-weighted figure is more consequential than the validator count alone. Solana’s voting power depends on the amount of SOL delegated to each validator, meaning 151 operators controlling 20.3% of stake represent a substantial share of the network’s consensus weight.

Alpenglow’s Consensus Overhaul

The central objective of Alpenglow is to reduce Solana’s time to finality. Its new voting component, Votor, is designed to bring finality down from roughly 12.8 seconds to about 150 milliseconds.

The upgrade retires TowerBFT, Solana’s existing voting mechanism, and replaces its one-by-one vote processing with an architecture built around aggregated BLS signatures. The active validator set will also be capped at 2,000 validators, ranked by stake weight.

Support for the overhaul was nearly unanimous: the proposal received 98.27% approval in September 2025. Testing continued across multiple network environments throughout 2026, but only the first phase is scheduled to go live in October. That phase includes Votor, VAT, and the BLS key requirements, while additional enhancements are planned for later stages.

What This Means

The readiness gap creates a short-term coordination risk, particularly because the unprepared validators account for a meaningful portion of voting stake. If operators fail to update in time, their ability to participate in consensus could be affected as the new requirements take effect.

At the same time, the snapshot shows significant progress. Earlier trackers estimated that approximately 45% of stake, or roughly 198 million SOL, did not meet all Alpenglow criteria. The decline to 20.3% suggests validators have been upgrading rapidly ahead of activation.

For Solana, a successful rollout would establish a faster consensus foundation while placing greater emphasis on validator maintenance, cryptographic key management, and the economics of participation. The next milestone is whether the remaining stake can become compliant before the scheduled switch.