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Cardano enacts Van Rossem hard fork, first Voltaire-ratified upgrade goes live

Cardano crossed the Van Rossem hard fork boundary on July 18 at 21:44:51 UTC — Protocol Version 11, ratified entirely through on-chain Voltaire governance without an IOG or Cardano Foundation trigger.

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Cardano crossed the Van Rossem hard fork boundary on July 18, 2026 at 21:44:51 UTC (start of a new epoch), moving mainnet to Protocol Version 11. It is the first Cardano hard fork ratified end-to-end through the network's Voltaire on-chain governance — a governance action, three separate voting bodies, thresholds crossed, no manual trigger by Input Output, Emurgo or the Cardano Foundation. The upgrade adds new Plutus built-in functions and lowers smart contract execution costs; it is an intra-era change inside the Conway ledger era, so there is no ledger schema break. Primary references: Cardano Foundation's Van Rossem hard fork announcement, the hard fork tracker on cardano.org, and Intersect MBO's governance-action write-up. Independent coverage: Crypto Briefing, crypto.news and PrimeXBT News.

What happened

The hard fork initiation action was submitted to mainnet on June 16, 2026 during Epoch 637. Under Voltaire, three constituencies had to sign it off separately:

  • Delegated Representatives (DReps) — stake-weighted representatives that ADA holders delegate to.
  • Stake Pool Operators (SPOs) — stake-weighted validators.
  • Constitutional Committee (CC) — a seven-seat body checking every action against the Cardano constitution.

At the epoch boundary on July 13, 2026 at 21:44:51 UTC, all three thresholds were satisfied at the same snapshot — the action was ratified. Enactment then followed after the mandated epoch offset, landing at the July 18 boundary. Nothing between ratification and enactment required a founding-entity action; the change was carried by the chain itself.

Mechanism — three tallies, one snapshot

The Voltaire hard fork rules are strict, and Van Rossem cleared them cleanly:

  • DReps: 77.63% in favour (threshold 60%).
  • SPOs: 52.7% in favour (threshold 51%).
  • Constitutional Committee: 6 of 7 members in favour, one abstention (threshold: constitutional majority).

An intra-era upgrade means the ledger's Conway schema does not change — accounts, UTxOs, staking objects and governance state stay compatible. What changes is at the plutus-core evaluator level: new built-ins are added (avoiding costly hand-rolled equivalents in scripts) and the Plutus cost model parameter set is updated so common script operations charge fewer execution units.

The upgrade is named after Max van Rossem, a Cardano community contributor who died earlier in 2026.

Numbers block

- Enactment                : 2026-07-18 21:44:51 UTC (epoch boundary)
- Slot at enactment        : 192,844,800
- Ratification             : 2026-07-13 21:44:51 UTC
- Governance action posted : 2026-06-16 (Epoch 637)
- Protocol version         : 11 (intra-era, Conway ledger)
- DReps in favour          : 77.63% (threshold: 60%)
- SPOs in favour           : 52.7%  (threshold: 51%)
- Constitutional Committee : 6 of 7 in favour, 1 did not vote
- Node readiness pre-fork  : ~93.5% of active stake on compatible clients
- Founding-entity triggers : 0 — no IOG, Cardano Foundation or Emurgo action
                             was required between ratification and enactment

Impact

For infrastructure operators, the boundary was a hard cutover. Any node still on Protocol Version 10 code past 21:44:51 UTC on July 18 is now off-chain and stops producing valid blocks — the network keeps running without it. Exchange deposit/withdrawal freezes over the boundary window were the standard operational tell in the run-up: Bitfinex, Binance, Kraken, KuCoin, OKX and Bybit all pre-announced pauses across July 17–18. Pre-fork node readiness telemetry read ~93.5% of active stake on compatible clients before the epoch boundary.

For developers, the practical read is cheaper on-chain compute. Plutus scripts that hit the newly added built-ins (or that previously spent execution units on hand-implemented cryptographic or serialisation primitives) should see meaningful budget headroom on their next audit, without any script-address change — the ledger's constraint envelope moves; the address model doesn't.

For governance, the political read is larger than the technical one. Every previous Cardano hard fork — from Byron→Shelley through Chang — was scheduled by IOG and the Cardano Foundation, then executed. Van Rossem is the first upgrade that no founding entity could have blocked once ratified: three on-chain constituencies voted, thresholds were crossed at an epoch boundary, and the network moved. The Voltaire architecture ships upgrades on its own now, or it doesn't. This one shipped.

Action checklist

  1. Stake-pool operators — confirm your node has moved to a Van Rossem-compatible release (Node v10.7+ line). If your pool missed the boundary and stopped forging blocks, upgrade before your next scheduled slot; there is no rewards-loss grace period beyond what pool minting logic already provides.
  2. Exchanges and custodians — reopen ADA deposits and withdrawals once your infra confirms two epochs of clean block production post-fork, per Intersect's operator guidance. Reconcile any in-flight transactions that straddled the boundary.
  3. Plutus developers — rebuild against the updated Plutus cost model before your next mainnet deployment. Cheaper compute is nice; a stale cost model is what silently triggers rejected scripts.
  4. DRep operators and delegators — the Van Rossem playbook is now the template. Read the ratified action from the on-chain governance state (via cardano-cli conway query gov-state or a govtool front-end) and treat the DRep participation ratios as the number your delegation choices are getting benchmarked against next cycle.
  5. Wallet vendors (Yoroi, Lace, Eternl, Vespr, GeroWallet) — verify that the client parses V11 metadata and displays the new script-cost readings correctly in fee previews.

Context — the third hard fork in Cardano's Voltaire era, the first without an escape hatch

The Voltaire era formally started with the Chang hard fork in September 2024, which introduced DReps and the Constitutional Committee but kept the founding entities as the practical mover for upgrades. Chang 2 in early 2025 activated the on-chain governance rails end-to-end. Van Rossem is the first hard fork where those rails did the work end-to-end without a founding-entity trigger — the escape hatch that Chang had implicitly left in the design is closed.

That closure sits inside a wider pattern this year: the Cardano Foundation cancelled its 2026 Summit after a governance treasury vote fell just short in late May; Emurgo stepped down from its Pentad governance role earlier in July; the DRep vote-participation ratios keep climbing epoch on epoch. Voltaire is not a stable equilibrium yet, and there are still open questions about DRep concentration, quorum bar-raising and the Constitutional Committee's mandate renewal timeline. But Van Rossem is the first change to mainnet that no one at IOG or the Cardano Foundation could have stopped once the on-chain thresholds were crossed. On paper, that was the point of Voltaire from the start. Now it's proven at the epoch boundary.

The next reads on this arc: whether the Leios scaling upgrade — currently being staged on PreProd — reaches a governance action within Q3, and whether the Dijkstra ledger era transition later this year continues to be delivered through the same on-chain path. The technical roadmap is now downstream of the governance one.

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