Cardano activated Protocol Version 11 on June 28, 2026, making Van Rossem the first hard fork in the chain's history ratified entirely through Voltaire on-chain governance rather than by IOG alone.
The upgrade cleared Cardano's three-body ratification process across delegated representatives, the Constitutional Committee, and stake pool operators. DReps voted 83.62% in favor, representing 4.44 billion ADA in backing, per crypto.news. Ratification by all three bodies marks the first time Cardano's governance framework has completed its full Voltaire process.
Van Rossem is an intra-era fork, meaning it adds capabilities while keeping Cardano inside the current era and limiting disruption to wallets, exchanges, and applications. The changes include Plutus smart contract performance improvements and ledger consistency fixes. The upgrade also lays the foundation for the Dijkstra era, which is expected to eventually enable Leios, Cardano's planned high-throughput scaling design, per crypto.news.
The governance action was submitted June 16, 2026, in Epoch 637, with June 28 the earliest eligible enactment date. In the five days through June 12, 84% of block production on Cardano mainnet came from Protocol Version 11 nodes, per Yahoo Finance, indicating network readiness ahead of the governance schedule.
The fork is named after Max van Rossem, a Cardano contributor who died in October 2025, per crypto.news. Intersect, the member-based organization managing Cardano's development roadmap, described him as a developer, stake pool operator, DRep, Constitutional Convention delegate, and builder in the ecosystem who "asked hard questions," "built," and "showed up."