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Alpenglow Migration Starts on Testnet: Solana's New Consensus Enters the Hot Phase

Anza's tracker lists the testnet migration from epoch 1042 as SIMD-0326. The new overview page names SIMD-0384 as the migration gate. No mainnet date is confirmed.

SOLANA·HUB Editorial
Source: Anza

What Happened

Anza has announced the formal migration of the public Solana testnet from TowerBFT to Alpenglow: the feature gate SIMD-0326 activates at epoch 1042 — per the schedule, today — with the switchover itself running across roughly 5,000 slots. Testnet validators are to upgrade to Agave v4.3.0 beforehand. It is the largest consensus change in Solana’s history — and the last major step before mainnet.

Two constraints straight from the announcement: Firedancer and Frankendancer do not participate in the migration phase — their Alpenglow support follows after the transition. And this is a testnet activation, not a mainnet launch; there is no confirmed mainnet date. The circulating September 28 comes from Anza’s Agave 4.3 release schedule, where, per Anza, it marks the resumption of regular feature activations on mainnet — not an Alpenglow date. According to Anza, the usual protocol applies: testnet first, then devnet, then mainnet after an observation period. The target corridor remains the October from the Foundation’s schedule.

What Changes Technically

Alpenglow replaces the current voting model: on-chain vote transactions give way to the off-chain voting protocol Votor, with vote accounts carrying a BLS key going forward. The data interface changes with it: the Dragon’s Mouth gRPC stream gains a new blockFooter. Indexers, explorers, and monitoring that evaluate votes or finality status must handle the new fields.

The promise behind it is finality: instead of the current ~12.8 seconds to full finalization, the design targets a magnitude of ~150 milliseconds. That is the design target from the Alpenglow paper — what the testnet delivers under real load is what the migration phase will show, and testnet numbers are no mainnet guarantee.

The Road Here

The step follows the pattern of the rollout stages so far: first the community test cluster in May, then the bug bounty program, now the public testnet. How the new consensus works in detail is covered in our explainer Alpenglow: Solana’s New Consensus.

Update (September 24, 2026): Votor Now Finalizes the Testnet

The switchover is done. After the feature gate activated, a 5,000-slot countdown ran, per Anza; at the migration boundary, validators confirmed the final TowerBFT block with 82 percent of stake. According to Anza, the handoff completed at slot 444,625,255: the Alpenglow genesis block has formed and TowerBFT is retired on testnet. Since then, testnet finalizes with Votor, and votes have moved entirely off-chain.

Ilan Gitter, Head of Ecosystem Engineering at the Solana Foundation, reported a handoff without issues and cited 25,000+ TPS with 150ms finality for the testnet cluster. That is a self-reported testnet figure, not a mainnet value. Anza names devnet as the next step, with mainnet-beta following after an observation period. No date is set for either. Firedancer and Frankendancer were, as planned, not part of the migration; background on the clients in Firedancer and Frankendancer explained.

Update (September 25, 2026): Alpenglow Now Runs on Devnet Too

One day after testnet, devnet switched over as well. According to Anza, the handoff completed at slot 504,148,999: the Alpenglow genesis block has formed and TowerBFT is retired on devnet. Anza is calling on app developers to test their programs and integrations now, during the observation period ahead of the mainnet-beta migration. Anza still names no mainnet date.

Update (September 27, 2026): Anza Pushes Back on a September 28 Mainnet Date

Roger Wattenhofer, Head of Research at Anza and a professor at ETH Zurich, pushed back on reports that Alpenglow would activate on mainnet on September 28. A consensus protocol is not activated after only a few days of testing, he wrote on X. The order therefore stays testnet, devnet, then mainnet after an observation period; per Anza, September 28 concerns the resumption of regular Agave 4.3 feature activations. Our Alpenglow status page shows the current state per network.

Update (September 30, 2026): 54ms Median on Testnet

Anza Head of Research Roger Wattenhofer has published first measurements. On testnet, Votor finalizes at a median of 54 milliseconds, per his analysis; the Alpenglow paper had named 150ms as the target. On testnet, the range runs from about 25ms (10th percentile) to about 90ms (90th percentile), per Wattenhofer, mainly depending on how close validators are to each other geographically. Only the voting phase (Votor) is measured, not the dissemination of block data. Values differ between the test networks because stake distribution and load differ; testnet values are not a mainnet measurement.

Note: This is reporting, not investment advice.

Update (October 9, 2026): SIMD-0384 Describes the Migration, the Tracker Says SIMD-0326

Anza’s overview page names SIMD-0384 as the migration feature gate. The proposal SIMD-0384 is titled “Alpenglow migration”, depends on SIMD-0326, and specifies the handoff: activation at an epoch boundary, a migration boundary 5,000 slots later, and a genesis certificate at 82 percent of stake. The SIMD text gives the feature key a1penGLz8Vm2QHYB3JPefBiU4BY3Z6JkW2k3Scw5GWP.

The gate that activated on testnet at epoch 1042 and on devnet at epoch 1167 is listed in Anza’s feature-gate tracker as SIMD-0326. The key is A1pengvuM6JEcyNuTnMqepBKhwHE3N6PmUrdATGawhJS, titled “Alpenglow: new consensus algorithm”. Agave’s feature set uses the same label. SIMD-0384 and the key a1penGLz… do not appear in that tracker or in the feature set checked for this update. The wording in the opening, that the testnet migration feature gate is SIMD-0326, matches the tracker. It is not the label the overview page uses for the migration gate. The page names no mainnet date. On mainnet, the tracker still lists SIMD-0326 under “Pending Mainnet Beta Activation”.

What to Watch

  • How long the observation phase on testnet and devnet lasts
  • When Anza names a date for the mainnet migration
  • Which SIMD number Anza uses for the mainnet gate
  • When Firedancer follows with Alpenglow support

Sources

#alpenglow #anza #konsens #testnet #validator

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