Solana The largest network upgrade in history is about to arrive.
Alpenglow is a consensus upgrade that was first announced in May 2025, and now its activation date has finally been determined. Solana, the largest network improvement in history, is expected to go live on the mainnet at around 14:50 on October 21st. UTC.
What is Alpenglow? What changes will it bring to Solana? If I hold or stake $SOL, what do I need to do?
What is Alpenglow?
Alpenglow was designed by Anza and is a network upgrade aimed at replacing TowerBFT. TowerBFT has been the system used for consensus on this chain since Solana went live in March 2020. After completing the migration exercises on the community cluster, test network, and development network, Alpenglow is scheduled to be activated on the Solana mainnet on October 21st.
Alpenglow has redesigned the voting mechanism used when Solana reaches a consensus. Without delving into technical details, the implementation of Alpenglow has brought several key improvements to the Solana mainnet:
- The final transaction confirmation time has been reduced from 12.8 seconds to 12 milliseconds, an improvement of 85 times.
- Voting transactions are moved off-chain to free up block space and reduce the operational costs for validators.
- The fault tolerance has been increased from 33% to 40%, making Solana more resilient to malicious attacks.
This might be the most anticipated upgrade in history, as the developers of Solana and the broader community are all celebrating the upcoming activation.
Although the improvement in the final confirmation time of transactions is already quite significant, what the Solana validator community looks forward to even more is a reduction in operating costs. Under the TowerBFT mechanism, validators are required to pay 0.000005 SOL for each transaction, which is approximately 1.1 $ SOL per day, in order to help the network reach consensus.
Under Alpenglow, these votes will be transferred off-chain. Verifiers will no longer charge per individual transaction, but instead pay $0.8 SOL for each epoch. This represents a slight improvement for the operators.
I hold $ SOL. What do I need to do?
As Alpenglow is expected to go live on the mainnet, certain roles among network participants may need to take action to ensure a smooth migration, such as developers and validators.
- $ SOL Holders and Stakers: No action is required. You do not need to do anything, so please ignore any messages sent by impostors that attempt to induce you to sign transactions.
- Developer: Alpenglow will change the way blocks are generated, transmitted, and finally confirmed. For more details and to find out if your application will be affected, please refer to the migration checklist.
- Validator Operator: Before epoch 1064, make sure you are running a client based on agave and using a version built on Agave 4.3. Please maintain at least 0.8 $ SOL in your voting account to cover the Alpenglow fees according to the epoch.
For the 376 validators running Jito BAM, Jito has informed that the BAM node will temporarily enter maintenance mode. Jito recommends upgrading to v4.3.0-jito.0 before the migration, but operators should refer to official communications as the activation date approaches.
Alpenglow What will happen next?
The activation of Alpenglow marks a key step in a roadmap that was first proposed in May 2025. Following the initial deployment, Anza will continue to advance the future iterations of Alpenglow, which includes replacing the multi-layer tree structure of Turbine with a single relay hop.
Other future improvements also include starting block production before final confirmation in order to shorten the switching time between leaders and reduce the geographical distance between them.
