Cardano's Van Rossem Fork Activates, Proving the Blockchain Can Now Vote Its Own Hard Forks 🗳️

Cardano's Van Rossem hard fork activated on Saturday at 21:44 UTC, moving the network's mainnet to protocol version 11 and setting technical groundwork for the planned Ouroboros Leios scaling upgrade expected in late 2026. Onchain data from Cardanoscan shows Cardano moved from version 10 in epoch 643 to version 11 in epoch 644, with the change taking effect on July 18 and having been ratified on July 13.

The upgrade is the first in Cardano's history to be initiated, debated and ratified entirely through the protocol's onchain governance system rather than being coordinated top-down by founding developer Input Output. Van Rossem carries the name of Max van Rossem, a Dutch Cardano contributor who passed away in October 2025 and who served as a developer, elected representative, node operator and constitutional delegate. Three separate governance bodies had to sign off. Delegated representatives voted 77.63% in favor against the 60% threshold required, while stake pool operators backed the change at 52.7%, just clearing the required 51%. The seven-member Constitutional Committee, which rules only on whether proposals comply with the Cardano Constitution rather than on their merits, unanimously found the hard fork compliant.

On the technical side, the upgrade bundles Plutus improvements and Plutus Cost Model enhancements designed to lower smart contract execution costs, alongside new cryptographic primitives for faster digital-signature verification and a security fix requiring every stake pool to use a unique cryptographic key. Input Output described the changes in a weekly development report on Friday, writing that, "As well as Plutus improvements and Plutus Cost Model enhancements, this upgrade lays the foundation for the next upgrade, the Dijkstra era hard fork, which will introduce Ouroboros Leios to Cardano." Ouroboros Leios is a scaling proposal for Cardano's Ouroboros proof-of-stake consensus, intended to drastically increase transactions per second without weakening security guarantees.

For everyday $ADA holders and users, transaction shape stays the same under protocol version 11, though builders gain cheaper, more capable smart-contract execution. Cardano has been building toward this governance model since the 2024 Chang hard fork first introduced onchain voting, followed by the Plomin hard fork in early 2025, which gave token holders real decision-making power.