Intersect Submits Van Rossem Hard Fork Action on Cardano Mainnet, Honoring Max van Rossem

Intersect announced that the van Rossem hard fork initiation governance action has been submitted on the Cardano mainnet. The action moves Protocol Version 11 into the next stage of on-chain governance, where DReps, the Constitutional Committee and stake pool operators take part in the approval process before any mainnet enactment.

The proposed upgrade is an intra-era hard fork, meaning Cardano remains within the Conway era while introducing new protocol features. Intersect described the upgrade as a step that lays the foundation for the next major era, Dijkstra, which is expected to bring Leios to the Cardano mainnet. The hard fork is named after Max van Rossem, a Cardano community member who contributed as a developer, stake pool operator, DRep and Constitutional Convention delegate.

Van Rossem Hard Fork Action Submitted on Cardano Mainnet

The van Rossem hard fork action proposes Cardano’s move to Major Protocol Version 11 and Minor Version 0. According to Intersect, the mainnet submission followed a special Hard Fork Working Group meeting on June 15, 2026, with support from the Intersect Technical Steering Committee. The action was submitted during epoch 637 on June 16, 2026.

The submission does not activate the hard fork immediately. It begins the mainnet governance phase for the hard fork initiation action, with approval required through Cardano’s on-chain governance system. The action has an expiration date of July 18, 2026, if the process is not completed before then.

The final timing now depends on governance approval and the relevant epoch boundary, with mainnet enactment possible from late June into July 2026.

The mainnet submission follows earlier testnet work. Preview moved to Protocol Version 11 on May 8, 2026, while PreProd enacted the hard fork on June 10, 2026 at 00:00 UTC. The related Plutus Cost Model parameter update on mainnet has already been ratified, with enactment scheduled for June 18, 2026 at 21:45 UTC.

Protocol Version 11 Adds Plutus and Ledger Updates

Protocol Version 11 includes changes across Plutus, ledger rules and node infrastructure. One of the central Plutus changes is the alignment of built-in functions across Plutus V1, V2 and V3. This expands available functionality for older Plutus script versions and reduces differences between smart contract generations.

The upgrade also introduces new built-ins and native types. These include the Array type from CIP-138, the MaryEraValue type from CIP-153, modular exponentiation from CIP-109, dropList from CIP-132 and multi-scalar multiplication over BLS12-381 from CIP-133. These additions are relevant for advanced cryptographic operations, data handling and more complex on-chain application development.

The update also adds support for case expressions over built-in Bool, Integer and Data types inside Untyped Plutus Core. This is intended to improve script logic and make data matching operations more efficient.

On the ledger and node side, the upgrade includes enforcement of VRF key uniqueness for stake pools, revised reference input rules for Plutus V1 and V2 scripts, movement of selected Constitutional Committee voting restriction checks into ledger rules, clearer handling of non-matching withdrawals predicates and improved reporting for protocol parameter hash mismatch cases.

Cardano-node 11.0.1 has already been released as the first node version supporting the Protocol Version 11 hard fork. The release enables the network to move to Protocol Version 11 once the governance action is approved and enacted on-chain.

Governance Vote Carries a Community Dedication to Max van Rossem

The van Rossem hard fork also carries a formal community dedication. The name honors Max van Rossem, who died in October 2025 and was active across several parts of the Cardano ecosystem. Intersect described him as a dedicated builder, developer, stake pool operator, DRep, Constitutional Convention delegate and wider community contributor.

Following his death, the Cardano community voted in early 2026 to dedicate the Protocol Version 11 hard fork in his honor. The info action, titled “Name Protocol Version 11 hard fork, van Rossem,” received 83.62% DRep support and 4.44 billion ada in voting support.

A lasting dedication to Max van Rossem has also been included in the proposal metadata. The naming places the hard fork within both Cardano’s technical upgrade path and its governance record, linking the Protocol Version 11 process with a community decision made before the mainnet submission.

Until enactment, the van Rossem hard fork remains an active governance action. Its next steps depend on on-chain voting, readiness tracking and the required governance thresholds. If approved and enacted, Protocol Version 11 will introduce new Plutus functionality, refined ledger rules and a mainnet upgrade process carried forward under Cardano’s Voltaire governance framework.