A hard fork is one of the most visible and celebrated moments in Cardano development, but rarely is it the work of a single team or a single decision.
By the time a hard fork reaches Mainnet, there will have been months of intense testing, coordination, trials, errors, governance discussions, infrastructure upgrades, and debates.

The van Rossem upgrade has been no exception to the above. While much of the conversation surrounding it understandably focuses on the technical changes being introduced, ing the journey to enactment provides a useful insight into Cardano’s governance processes working in practice across developers, infrastructure providers, DReps, SPOs, founding entities, and our wider community.

With this in mind, it is an appropriate time to thank all of those that have been involved in the Hard Fork Working Group (HFWG) to get us to this point. Including contributors from Input Output, Cardano Foundation, Emurgo, Midnight and Ensurable Systems, among so many others. All coordinating under the Intersect Hard Fork Working Group, in collaboration with the Intersect Technical Steering Committee. A reminder that the role of an MBO works well for technical coordination and managing a stable upgrade.

The state of play

Progress towards the van Rossem hard fork on Cardano Mainnet has been continuing across the Preview and Preprod test networks throughout the months of May and June 2026. The process has primarily involved two governance actions; a Plutus Cost Model (PCM) parameter update action and a hard fork initiation action.

Why two governance actions?

The Plutus Cost Model parameter update brings two key changes that take effect at two different stages. First of all, it contains increases in the cost model of some existing primitives. These take effect immediately after enactment and so it is vital that DApps and developers are prepared and have adjusted their settings accordingly if needed. Secondly, the update is preferred before the hard fork as it provides the settings for new primitives enabled by the hard fork itself, allowing them to be utilized immediately after hard fork enactment.

What has happened so far?

ing the parameter update on April 17, 2026 at 00:00 UTC and the release of and early in May, the Preview test network to protocol version 11 onat 00:00 UTC.

On the Preprod test network, the parameter update was enacted onat 00:00 UTC with DApps and developers highly encouraged to test their setups against the recent increases in a small number of existing primitives before progression to Mainnet. Although the hard fork initiation action was to Preprod on, ratification was held back while a resolution regarding Ogmios and Kupo tooling hard fork compatibility could be found.

The decision was made for Intersect to host forks of and that could be made hard fork compatible, allowing testing to continue on Preprod. This seemingly small operational detail was a reminder that successful upgrades often