Solana Foundation said the Alpenglow upgrade should reduce transaction finality on the Solana network from approximately 12.8 seconds to about 150 milliseconds. Activation is expected to take place via Agave 4.3, targeting October, according to the foundation.
The network's official documentation projects the Alpenglow release for the 3rd quarter of 2026. The possibility of the feature arriving as early as September, however, is not treated as confirmed.
Finality and confirmation
Finality is different from transaction confirmation. On Solana, the user already receives a quick confirmation, with the slot time being reduced from 400 ms to 200 ms. But confirmation does not represent the network's strongest level of consensus. In an extreme situation, the chain can be reorganized and a previous state reverted.
Finality is the mechanism that gives applications the guarantee that the observed state will not be reverted. With the current TowerBFT consensus, that guarantee takes about 12.8 seconds. Alpenglow seeks to compress this process to approximately 150 milliseconds.
Solana co-founder Anatoly Yakovenko said that finality is "really important only at the cash register." He cited the example of a cryptocurrency purchase: the merchant can accept the transaction after quick confirmation, but, in higher-value payments, may require a stronger guarantee that the payment does not disappear from the canonical chain.
For the average user, the change may not seem as drastic as the numbers suggest.
