Alpenglow Mainnet Launch Not Happening Sept 28, Solana Devs Say

The Alpenglow mainnet will not launch on September 28, contrary to earlier reports. Solana co-founder Anatoly Yakovenko responded to the speculation with one word: "decel."

Alpenglow is an overhaul of the consensus layer aimed at achieving 150-millisecond finality, compared to the current roughly 12.8 seconds for full finality. Several publications had also cautioned that SOL could decline if the upgrade were delayed.

Alpenglow Launch Date Linked to Validator Schedule

Roger Wattenhofer, who leads research at Anza and is a professor at ETH Zurich, countered the reports on X. Anza is the developer of Agave, Solana's primary validator client.

Why would we test a protocol for only a few days before activating it? There is no Alpenrush.

He noted that Alpenglow had only recently entered public testing.

Yakovenko then cited that post and added "decel," a crypto term meaning to slow down. The opposite, "accel," indicates a push to speed up.

decel https://t.co/dmpOKITSNS

— toly 🇺🇸 (@toly) September 27, 2026

The date probably originated from Anza's Agave v4.3 release schedule, which shows September 28 as the date for resuming feature activation on mainnet. That schedule, however, does not mention Alpenglow.

Meanwhile, the subsequent v4.4 timeline indicates a mainnet activation window starting November 9. Anza describes that schedule as tentative, and it also does not reference Alpenglow.

SOL Price Largely Unfazed by Clarification

At press time, Solana (SOL) was trading at $119.85, a 0.36% decline over the past 24 hours, per BeInCrypto Markets data. The limited price movement indicates that few traders had anticipated a September 28 mainnet launch for Alpenglow.

This caution is set against a recent incident. In August, a routing issue brought Solana near a network halt. Given that history, Wattenhofer's remarks imply that developers aim to avoid a hasty consensus upgrade.

Alpenglow is not the only speed enhancement underway. In August, Solana started reducing its block time from 400 to 200 milliseconds. That modification accelerates block production, whereas Alpenglow focuses on how fast blocks achieve finality.

Solana has been readying validators for Alpenglow since July. For the time being, the upgrade remains on testnet, and neither Agave schedule assigns it a mainnet launch date.