Solana has activated Alpenglow, its largest consensus upgrade since the network launched, replacing the TowerBFT protocol and reducing the time needed for transactions to become irreversible from about 12.8 seconds to roughly 150 milliseconds.
The upgrade went live on Solana’s mainnet-beta on Wednesday at slot 459,653,000, at approximately 14:00 UTC, according to core engineering team Anza. Validators moved from TowerBFT to Alpenglow while preserving the network’s existing ledger. Independent operators coordinated the handoff at a shared activation point.
The change affects finality—the stage at which a transaction can no longer be reversed. That distinction matters for exchanges, banks and merchants, which generally wait for finality before treating an asset transfer as complete. Under TowerBFT, Solana could provide a conditional confirmation within seconds, but full finality took approximately 12.8 seconds. Alpenglow combines those stages into a much faster process.
What Alpenglow changes
TowerBFT had been Solana’s consensus protocol since March 2020. Alpenglow changes how validators communicate and approve blocks. Instead of recording votes in later blocks, validators send votes directly to one another, with voting power weighted by each validator’s stake.
The protocol can finalize a block when 80% of voting power supports it, according to an explanation from Anza research chief Roger Wattenhofer. A second mechanism uses two voting rounds, each requiring 60% of stake, and may be faster when validators are located close to one another, such as within Europe.
Alpenglow is designed to continue operating if less than 20% of stake behaves maliciously and another 20% is offline. If no block is finalized for 10 seconds, validators gradually increase block times to allow delayed network messages to arrive. The purpose is to let the network recover even when internet conditions are poor.
The protocol was designed by Anza’s research team, led by Wattenhofer of ETH Zurich alongside Quentin Kniep and Kobi Sliwinski. The design was published in May 2025, and Anza implemented it in Agave, the validator software it maintains. Independent validators then activated the change on the live network.
From approval to mainnet
Solana validators approved the upgrade in September 2025, with 98% voting in favor of SIMD-0236, the proposal that introduced Alpenglow. Before mainnet activation, the upgrade underwent public testing that included red-team exercises, penetration testing, migration rehearsals and a security competition.
It was subsequently launched on Solana’s testnet and devnet, followed by activation on the community test cluster in May 2026. Anza had previously targeted a mainnet launch for late in the third quarter or early in the fourth quarter of 2026, and confirmed October 21 as the activation date on October 13.
Anza CEO Brennan Watt described the project as the “largest, most ambitious blockchain upgrade since ‘The Merge,’” referring to Ethereum’s 2022 move to proof of stake. He said Anza took Alpenglow from a white paper to a running mainnet system in less than 18 months. The original reporting was published by Decrypt.
The quicker finality is intended to improve the experience of organizations that need rapid certainty over a transaction’s status. It does not mean that every aspect of Solana’s infrastructure has changed at once: Alpenglow specifically replaces the consensus mechanism and changes how quickly blocks become irreversible.
Further upgrades remain ahead
Alpenglow is also intended to provide a foundation for additional changes, though those projects do not have committed launch dates. Rotor is planned to alter how block data moves through the network. Another proposal would make leader rotation geographically aware, potentially reducing delays as block production shifts between validators.
A separate research design, Quantumglow, would replace Alpenglow’s elliptic-curve cryptography with hash-based signatures. The stated aim is to make the system resistant to quantum computers while maintaining the same finality speed.
Developers associated with Jump Crypto’s Firedancer project have also proposed removing Solana’s current limit of 60 million compute units per block after Alpenglow goes live. Under that proposal, blocks could expand to the capacity supported by the fastest validators, while slower validators could use a “skip vote” option to abstain. Critics have cautioned that such a change could favor better-funded operators and raise centralization concerns.
Current market picture
Moneyiar market data as of October 22, 2026, at 23:34 local time show Solana’s SOL trading at $103.2286130606, down 3.5% over 24 hours and 1.95% over seven days.
Ethereum’s ETH was priced at $2,380.8237081254, falling 3.85% over 24 hours and 2.39% over seven days. Shiba Inu’s SHIB stood at $0.0000049354, down 4.28% in 24 hours and 3.39% over seven days, while Uniswap’s UNI was $6.9729497991, down 6.6% and 6.07% over the same periods, respectively.
