The Cardano Van Rossem hard fork and on-chain governance process saw Cardano activate the Van Rossem upgrade and transition the live network to protocol version 11. The Van Rossem upgrade is the first major Cardano upgrade ratified entirely through on-chain governance, and it was approved without input from the founding development company. Three governance bodies participated in the approval process: elected delegated representatives (DReps) acting on behalf of Cardano holders, stake pool operators, and a Constitutional oversight committee that together cleared the upgrade for deployment, in a fully on-chain community vote process.
The Van Rossem upgrade implements protocol version 11 features on Cardano, bringing a collection of specific low-level and runtime enhancements defined as protocol-version-11. These protocol-version-11 changes include constant-time array indexing, native Value handling, faster list traversal, and new cryptographic primitives, and they were introduced as part of the network upgrade labeled Van Rossem. The upgrade also deploys built-ins across Plutus V1, V2, and V3, incorporating those runtime functions into the various Plutus versions supported by the chain.
Van Rossem is described as an intra-era, targeted upgrade aimed at lowering Plutus execution costs rather than a full rework of the protocol architecture. The upgrade is explicitly characterized as not rebuilding Cardano’s core structure and instead applying focused improvements within the existing era. The protocol-version-11 feature set is therefore implemented within this intra-era scope with the stated objective of reducing Plutus execution cost burdens.
Three governance bodies approved the Van Rossem upgrade: delegated representatives (DReps), stake pool operators, and the Constitutional Committee. Delegated representatives—community members elected to vote on behalf of Cardano holders—approved the proposal with 77.63% support, exceeding the 60% threshold. Stake pool operators approved the upgrade with 52.7% support, clearing the 51% threshold required for their group. The Constitutional Committee also approved the upgrade as the oversight committee involved in the governance process.
The upgrade was ratified entirely through on-chain governance without input from the founding development company Input Output Group. On-chain governance had been a stated development goal following the Chang hard fork in 2024 and the Plomin hard fork in 2025. The approval therefore reflects votes cast by elected community representatives, stake pool operators and the Constitutional oversight body within the on-chain governance framework.
The Van Rossem upgrade roll-out occurred over the weekend and the upgrade is live on the Cardano network. For everyday Cardano users, no immediate changes are noticeable following the deployment and routine usage should appear unchanged. The deployment also includes a security fix that requires every stake pool to use a unique cryptographic key as part of the upgrade.
On-chain governance has been a development goal for Cardano since the Chang hard fork in 2024 and the Plomin hard fork in 2025. This section addresses operational impact and recent context without restating governance voting details or low-level technical mechanisms. It does not provide operational instructions for node operators or additional technical guidance.
The Van Rossem hard fork is a major intra-era Cardano upgrade ratified through on-chain governance with broad community approval and implemented as protocol version 11. It was approved by elected delegated representatives, stake pool operators and the Constitutional Committee, and its stated technical goals include lowering Plutus execution costs and supporting improved scalability to reduce costs for smart-contract execution.
