Solana is scheduled to activate its Alpenglow upgrade on mainnet on October 21 at around 15:00 UTC, replacing the consensus mechanism the network has used since launch. According to core developer Anza, the change is designed to cut transaction finality from about 12.8 seconds to roughly 150 milliseconds.

The upgrade marks a major change to how the network reaches consensus and reports activity. It also arrives with some uncertainty: a previous Alpenglow activation date of September 28 was announced and later delayed, and the second phase of the broader rollout still has no confirmed date.

Consensus change set for one-slot migration

Anza described Alpenglow as the product of 18 months of work and said the migration is expected to happen in a single slot. Once live, it will retire the system Solana has relied on since the network launched.

In practical terms, finality is the point at which a transaction is no longer reversible. Solana transactions have often appeared nearly instant to users, but there has still been a window of roughly 13 seconds in which a block could theoretically be dropped. Exchanges and payment processors have had to account for that timing in their own systems.

Target is faster confirmation and more resilience

The stated goal of Alpenglow is to reduce that waiting period dramatically. Anza said the target is about 150 milliseconds, compared with the current roughly 12.8 seconds, a change the developer framed as about 85 times faster.

The source article also says the old system can fail if more than around one third of staked SOL behaves maliciously. Under Alpenglow, the new design is intended to keep finalizing even if 20% of stake acts maliciously and another 20% is simply offline. That resilience claim is likely to matter for firms evaluating reliability as much as raw speed.

Reported transaction counts may drop after launch

One immediate side effect of the upgrade is expected to show up on public dashboards. Today, validators submit their votes as transactions on-chain. Under Alpenglow, those votes are instead exchanged directly between validators off-chain.

Because of that shift, Solana's widely cited transaction count and transactions-per-second figures are likely to fall sharply after activation, even if user demand, trading volume, and application usage remain unchanged. The article warns that this could lead to misleading interpretations of a decline in activity when the change would mainly reflect a new accounting of validator communication.

Rollout is not fully complete yet

Alpenglow is described as the first of a two-phase effort, and no activation date has been given for the second part. That means next week's event is significant, but it does not represent the entire roadmap for the new system.

There is also precedent for schedule changes. A September 28 activation had previously been announced and then postponed, so the October 21 timing should still be treated as a plan until the upgrade is actually executed on mainnet. For now, the next confirmed step is the intended mainnet activation window at about 15:00 UTC on October 21.

Source: decrypt.co