Solana is about to undergo its largest network upgrade in history.
Alpenglow, a consensus upgrade first announced in May 2025, has now officially confirmed its activation date. Solana’s largest network upgrade to date is scheduled to go live on mainnet on October 21 at approximately 14:50 UTC.
What is Alpenglow? What changes will it bring to Solana? What do I need to do if I hold or stake $SOL?
What is Alpenglow?
Alpenglow, designed by Anza, is a network upgrade intended to replace TowerBFT, the system the Solana chain has used for consensus since its launch in March 2020. Following successful migration drills on community clusters, testnets, and devnets, Alpenglow is scheduled to activate on the Solana mainnet on October 21.
Alpenglow has redesigned how votes are processed during Solana's consensus process. Without delving into technical details, Alpenglow's implementation brings several key improvements to the Solana mainnet:
- Transaction final confirmation time has decreased from 12.8 seconds to 12 milliseconds, improving by 85 times.
- Voting transactions move off-chain, freeing up block space and reducing validator operational costs.
- Fault tolerance has been increased from 33% to 40%, making Solana more resilient to malicious attacks.
This may be the most anticipated upgrade in history, with Solana’s developers and the broader community celebrating the upcoming activation.
Although the improvement in final transaction confirmation time is already significant, the Solana validator community is even more eager for reduced operational costs. Under the TowerBFT mechanism, validators must pay 0.000005 SOL per transaction, or approximately 1.1 $SOL per day, to help the network reach consensus.
Under Alpenglow, these votes will be moved off-chain. Validators will no longer be charged per transaction but will instead receive 0.8 $SOL per epoch, offering a slight improvement for operators.
I hold $SOL—what should I do?
As Alpenglow prepares for mainnet launch, certain participants in the network, such as developers and validator operators, may need to take action to ensure a smooth migration.
- SOL holders and stakers: No action is required. You do not need to do anything, so ignore any messages from impostors attempting to trick you into signing transactions.
- Developer: Alpenglow will change how blocks are generated, transmitted, and finally confirmed. For more details and to determine if your application will be affected, refer to the migration checklist.
- Validator Operator: Before epoch 1064, ensure you are running an Agave-based client using a version built on Agave 4.3. Maintain at least 0.8 $SOL in your voting account to cover Alpenglow’s per-epoch fees.
For the 376 validators running Jito BAM, Jito has stated that BAM nodes will temporarily enter maintenance mode. Jito recommends upgrading to v4.3.0-jito.0 before migration, but operators should refer to official communications as the activation date approaches.
What’s next for Alpenglow?
The activation of Alpenglow marks a key step in a roadmap first publicly proposed in May 2025. Following its initial deployment, Anza will continue advancing future iterations of Alpenglow, including replacing Turbine’s multi-layer tree structure with a single relay hop.
Future improvements also plan to reduce the time between leader transitions and minimize the geographic distance between leaders by beginning block production before final confirmation.