Every so often a Cardano hard fork is a headline event, a new capability, a new train leaving the station that everyone has to board. The van Rossem hard fork is quieter than that on paper. It does not open a new era. It does not hand the community a dramatic new feature to show off. It is the eleventh hard fork in Cardano’s history, and only the second the network decided to do by itself, through on-chain governance, rather than having it handed down by the engineers who built it. The first was the Plomin hard fork, just over a year earlier. Two in a row is a good sign that global on-chain governance in the blockchain space might stand a chance.
At the time of writing, van Rossem is not yet live. It has been proposed and is rolling out; it becomes real only once the community’s votes clear and the network crosses the next epoch boundary. If you have followed this series, you will remember that the Chang hard fork built Cardano’s governance machinery, and the Plomin hard fork switched it fully on. That was the first upgrade the community pushed through by vote. van Rossem is the second. It is an excellent bookmark that Cardano’s ambitious attempt at how governing blockchain, companies, and event cities can be the job of everyone participating on the network, not just engineers.
First, what is a hard fork again?
A quick refresher, because it never hurts. A hard fork is simply a big update to the software a blockchain runs, big enough that every node has to upgrade for the network to keep moving in the same direction. Smaller tweaks can happen quietly in the background, but a hard fork is a coordinated moment: the whole network agrees to change the rules at the same block, together. Historically on Cardano, these upgrades were proposed and scheduled by Input Output (IO) and its partners, with stake pool operators signalling readiness. van Rossem changes who gets to make that call.
The Road to van Rossem
Cardano’s development was famously mapped out in five named eras, each introduced by a hard fork, each named after a figure from history or literature.
Byron (2017): the launch era. Basic transactions, moving Ada from wallet to wallet.
Shelley (2020): staking and decentralization, the shift from federated nodes toward a community-run network. The Allegra and Mary upgrades rode alongside it, bringing token locking and then native tokens and NFTs.
Goguen (2021): smart contracts, delivered by the Alonzo hard fork. This is where Cardano became programmable.
Basho (2022 onward): scaling and optimization. The Vasil hard fork improved throughput and performance, and this is the stream of work that includes Hydra and partner chains.
Voltaire (2024–2025): Governance. The Chang hard fork switched on the governance features described in CIP-1694, and the Plomin hard fork completed the job, unlocking full DRep participation and every category of governance action. When Plomin was enacted in January 2025, Cardano became a chain governed by its own community. DReps casting votes on behalf of delegators, stake pool operators, and a Constitutional Committee keeping decisions inside bounds defined in a constitution written by the global Cardano community. Plomin was also the first hard fork the community itself voted through.
Counting from the 2017 launch, van Rossem is the eleventh hard fork on that timeline. Protocol Version 11 and the hard-forks to date have kept pace with each other since Byron. For the complete list, Cardano keeps a public record at cardano.org/hardforks.
The van Rossem Hard Fork
van Rossem is Cardano’s move to Protocol Version 11, and only the second hard fork to run through the Voltaire on-chain governance framework rather than being decided by IO — the first having been Plomin (Protocol Version 10) in January 2025. There is a meaningful wrinkle, too: Plomin was enacted in the closing stretch of the governance bootstrap, whereas van Rossem is the first hard fork to run from start to finish under the fully live framework. Either way, there is no unilateral decision from IO. To go live, the upgrade has to clear three independent bodies, each with its own threshold:
DReps (delegated representatives) voting using the stake of ordinary ada holders have to approve the hard fork governance action.
The Constitutional Committee has to confirm the action as constitutional with a 5-of-7 sign-off.
Stake pool operators (SPOs) must actually run the new node software and vote on-chain, so the network was technically ready to switch.
Only when all three clear their bars can the upgrade proceed. This is what CIP-1694 was always for. A blockchain rewriting its own rules through a distributed, three-body vote. No single company is able to force or block it. This is genuinely rare in this industry. Most chains upgrade because a core team says so. Cardano upgrades only when its community says so — and that is exactly what is playing out with van Rossem right now.
What is actually in the upgrade
van Rossem is an intra-era hard fork, which means it does not launch a new ledger era at all. It stays inside the current Conway era and improves it in place. Under the hood, the most useful change is an update to the Plutus cost model. Plutus cost model is the pricing schedule that decides how much each smart-contract operation costs to run on-chain. In plain terms, van Rossem makes many smart contracts cheaper to execute. Alongside that, it adds a set of new Plutus primitives, and crucially makes all built-in functions available across Plutus V1, V2 and V3, so older contracts benefit too, giving businesses more time to upgrade their products. Each addition was discussed and approved via the less formal off-chain process as Cardano Improvement Proposals (CIPs):
- CIP-0109: an on-chain modular exponentiation built-in,
- CIP-0133: multi-scalar multiplication over BLS12-381. These are the mathematical building blocks of zero-knowledge cryptography, making Cardano meaningfully friendlier to ZK-based and privacy-preserving applications. For developers and businesses, it will be easier to integrate service providers like the Midnight Blockchain into your Cardano DApps.
- CIP-0132: a new dropList built-in
- CIP-0135: formalizes a disaster recovery plan.
- CIP-0138: a native Array type, so certain operations run faster and more predictably.
- CIP-0153: a native MaryEraValue built-in type, which lets contracts handle on-chain assets more efficiently.
Also included in the release are lower-level improvements to node security and ledger consistency, including stricter VRF key-uniqueness rules and updated handling of reference inputs. The gains are measurable documented in the Cardano Node 11.0.1 performance report that comes with the release.
None of these are flashy on their own. Together, they make transaction fees on DApps cheaper, open the door wider to privacy-preserving and ZK applications, and tighten the screws on the protocol’s security. It is a very Cardano kind of upgrade: incremental, careful, and quietly consequential.
The name behind the fork
Cardano’s hard forks are named after people, and van Rossem carries one of the most moving stories in that tradition. The upgrade honours Max van Rossem, a governance contributor and DRep whose work in the community left a real mark. He passed away on January 11, 2026, the same day his son, Max Louis Hans van Rossem, was born. A life ending and beginning on a single day, remembered in the ledger itself.
Fittingly, the name was chosen the Voltaire way. In early 2026, an on-chain DRep vote decided what Protocol Version 11 would be called, and the community backed the van Rossem tribute with more than 80% support. I was one of the most decisive governance votes the network had recorded. There is something apt about a hard fork that proves community governance works also being named by that same community, in memory of someone who helped build it.
How it goes live
van Rossem is following the measured path you would expect from a research-first chain. The changes were tested on the Preview and Preprod testnets first. On mainnet, the process is split into two coordinated governance actions — a Plutus cost-model parameter update and the hard fork initiation itself. From there, the decision leaves the engineers’ hands entirely.
Mechanically, the switch is thrown by the validators and the entire community. Stake pool operators upgrade their nodes and signal readiness on-chain through a Cardano Voltaire-era hard fork initiation governance action, the same transparent, publicly viewable mechanism used for every other governance decision. For the upgrade to actually go live, a few things have to line up:
- the DReps, the Constitutional Committee, and the stake pool operators each have to clear their voting thresholds;
- enough SPOs have to be running the new node version and signalling readiness on-chain;
- and only then does the hard fork trigger–at the next epoch boundary, a five-day handover point, the whole network switches to the new rules at the same point-in-time (slot), together.
That last detail is the part people new to Cardano often miss. A hard fork here is not a dramatic overnight switch; it is scheduled to a natural boundary in the chain’s clock so every node and business crosses over in lockstep. Readiness in the run-up has been strong. A large majority of blocks were already being produced by upgraded nodes. This is the signal that the network is prepared to make the jump. But until the votes clear and that epoch boundary arrives, Protocol Version 11 is proposed and pending. No drama, no single entity pulling the trigger. Just a network following its own rules to change its own rules.
Conclusion
It is tempting to measure a hard fork by the size of its feature list, and by that yardstick van Rossem looks small:
- cheaper contracts,
- new cryptographic primitives,
- security refinements
However, for the second time, and the first under the fully operational framework, Cardano is changing its own protocol through a decision that belongs entirely to its community: DReps voting delegated stake, a Constitutional Committee validating, and stake pool operators making it real. Once the votes clear and the epoch boundary passes, the three-legged governance model that CIP-1694 promised, and that Chang and Plomin built, will have carried the weight of a real protocol upgrade for a second time.
That is the quiet significance of van Rossem. Chang told us Cardano could govern itself. Plomin was the first upgrade the community voted through. van Rossem is the second, and two upgrades in, a community running its own hard forks starts to look less like a milestone and more like a habit. And it is doing so, fittingly, under a name that reminds everyone what this community is ultimately about — people showing up, contributing, and being remembered by the network they helped shape.
Cardano set out, from its first white paper, to make trust scalable, sustainable, and eventually self-governing. This is the kind of established, tried and tested foundation that governments and businesses can build their products and municipal services on without fear of security issues or long-term engineer uncertainties.
With the van Rossem hard fork, the self-governing part is turning from a roadmap item into a working habit. The next upgrades, scaling work like Leios chief among them, will travel this same road: proposed CIPs, debated, ratified, and enacted by the community itself. Measure twice, cut once, and this time, vote first.
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