TLDR: Cardano’s Van Rossem hard fork is the first upgrade approved entirely through onchain governance. Protocol Version 11 unifies Plutus built-in functions across versions V1, V2, and V3 ne
Cardano has completed its Van Rossem hard fork, activating Protocol Version 11 across the mainnet network. The Cardano hard fork marks the first upgrade approved entirely through onchain governance, without relying on centralized coordination.
Named after the late Dutch community leader Max van Rossem, the update introduces new Plutus primitives, unified built-in functions, and ledger-level improvements.
The Cardano hard fork also lowers smart contract execution costs while preparing the network for its upcoming Dijkstra era.
The Van Rossem upgrade moved the Cardano mainnet from Protocol Version 10 to Protocol Version 11. The change occurred through an intra-era hard fork, keeping the ledger within the Conway era. No era transition took place during the process.
Intersect’s Hard Fork Working Group recommended the governance action on June 15, 2026. The Technical Steering Committee endorsed the recommendation one day later. Both bodies confirmed the proposal met the required technical standards before submission.
The Cardano Constitution required at least 85% of stake pools by active stake to upgrade node software beforehand.
The relevant guardrail states that stake pools must move to “a Cardano node version that is capable of processing the rules” tied to the new protocol version. This threshold was verified by the Constitutional Committee and stake pool operators.
Testing reports confirmed no behavioral regressions across the network. Complete conformance was demonstrated between specification and implementation for new ledger rules. Performance benchmarks for Cardano Node version 11.0.1 showed no regressions compared to earlier releases.
Five Cardano Improvement Proposals introduced new Plutus primitives through this hard fork. These include CIP-0109, CIP-0132, CIP-0133, CIP-0138, and CIP-0153. Each proposal targets a specific performance or functionality gap in smart contract execution.
CIP-0109 adds a modular exponentiation built-in, supporting cryptographic operations like elliptic-curve calculations.
CIP-0132 introduces a dropList function, improving list-element access and redeemer-indexing efficiency. CIP-0133 enables multi-scalar multiplication over BLS12-381, supporting zero-knowledge proof verification onchain.
CIP-0138 brings a new Array type with constant-time indexing to Plutus Core. This replaces the previous singly-linked list structure for many use cases. CIP-0153 introduces a native Value type, streamlining multi-asset token handling within smart contracts.
Following the hard fork, all built-in functions became available across Plutus V1, V2, and V3. Untyped Plutus Core also gained case-expressions for Bool, Integer, and Data types. This replaces costlier conditional patterns that previously slowed script execution.
The hard fork strengthened several ledger-level protections during this update. VRF key hash uniqueness is now enforced at the ledger level, preventing duplicate stake pool registrations. This change mitigates certain attack vectors tied to VRF key reuse.
Reference input rules for Plutus V1 and V2 scripts were also revised. Constitutional Committee voting restrictions were promoted from mempool checks to ledger predicates. This change improves transparency across all transaction submission paths.
The hard fork carries the name of Max van Rossem, a Dutch community builder who passed away in October 2025.
He co-led the Constitutional Committee Election Working Group and represented the Dutch community at the Constitutional Convention in Buenos Aires.
Van Rossem founded AdaMoments and later Moments, guided by the belief that “user data = user’s data.” His son, Max Louis Hans van Rossem, was born on January 11, 2026. The Cardano hard fork now carries his father’s name into the network’s permanent history.
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