Cardano activated its van Rossem hard fork on July 18, 2026, completing the network's first protocol upgrade whose final approval and execution were determined entirely through its decentralized onchain governance system. The upgrade took effect at 21:44:51 UTC at the boundary of epoch 644, corresponding to Cardano slot 192,844,800, moving the blockchain to Protocol Version 11 while keeping it within the existing Conway ledger era. Unlike earlier Cardano upgrades that depended more heavily on the network's founding entities or temporary governance arrangements, van Rossem required formal approval from all three bodies established under Cardano's post-Chang governance framework: delegated representatives (DReps), stake pool operators, and the Constitutional Committee. This activation provides an operational test for Cardano's governance model, which was introduced progressively through the Chang and Plomin upgrades, demonstrating that these institutions can collectively authorize technically significant network changes without relying on offchain decisions by a central development company.
Cardano Governance Bodies Ratify Hard Fork Action on July 13
The hard-fork action was ratified on July 13 after receiving 77.63% support from DReps, above the required 60% threshold. Stake pool operator support reached 52.7%, narrowly clearing the 51% requirement, while six Constitutional Committee members voted that the action was constitutional. Five committee approvals were required, and one member did not vote.
The process required extensive coordination. Intersect, Cardano's member-based ecosystem organization, convened a Hard Fork Working Group involving Input Output, the Cardano Foundation, EMURGO, Midnight, infrastructure providers and other contributors. However, the group coordinated testing and readiness rather than possessing unilateral authority to activate the upgrade.
Van Rossem Hard Fork Activates at Epoch 644 Boundary
The upgrade took effect at 21:44:51 UTC at the boundary of epoch 644, corresponding to Cardano slot 192,844,800. It moved the blockchain to Protocol Version 11 while keeping it within the existing Conway ledger era, making van Rossem an "intra-era" hard fork rather than a broader transition to a new ledger architecture.
The intra-era structure lowers the integration burden compared with major transitions such as Chang because applications do not need to adopt a new transaction format.
Protocol Version 11 Introduces Plutus Smart-Contract Improvements
Van Rossem introduces targeted improvements to Cardano's Plutus smart-contract platform, ledger consistency and node security without changing transaction structure.
The upgrade makes a broader set of built-in functions available across Plutus V1, V2 and V3, reducing differences between script generations. It also adds more efficient case expressions for basic types and introduces native capabilities including arrays, optimized multi-asset value operations, modular exponentiation and improved list manipulation.
Additional changes include cryptographic improvements involving BLS12-381 operations and stronger uniqueness protections for stake pool verification keys. A related Plutus cost-model update was approved separately and enacted on June 18, allowing pricing parameters for the new functions to be available when the hard fork went live.
Testing Completes Across SanchoNet, Preview and Preprod Environments
Testing took place across the SanchoNet, Preview and Preprod environments. Preview moved to Protocol Version 11 on May 8, while Preprod completed its upgrade on June 10 after developers addressed compatibility issues affecting infrastructure tools including Ogmios and Kupo.
FAQ
What did Cardano's van Rossem hard fork accomplish on July 18, 2026?
Cardano activated its van Rossem hard fork on July 18, 2026 at 21:44:51 UTC, completing the network's first protocol upgrade whose final approval and execution were determined entirely through its decentralized onchain governance system. The upgrade moved the blockchain to Protocol Version 11 while keeping it within the existing Conway ledger era.
How did Cardano's governance bodies approve the van Rossem hard fork?
The hard-fork action was ratified on July 13 after receiving 77.63% support from DReps (above the required 60% threshold), 52.7% support from stake pool operators (clearing the 51% requirement), and approval from six Constitutional Committee members (five approvals were required, one member did not vote).
What improvements does Protocol Version 11 introduce to Cardano?
Protocol Version 11 introduces targeted improvements to Cardano's Plutus smart-contract platform, making a broader set of built-in functions available across Plutus V1, V2 and V3, adding more efficient case expressions for basic types, and introducing native capabilities including arrays, optimized multi-asset value operations, modular exponentiation, improved list manipulation, and cryptographic improvements involving BLS12-381 operations.
