Cardano's First Democracy-Driven Hard Fork Goes Live — Leios Loading 🧱

Cardano activated the van Rossem hard fork on Saturday, moving the network from Protocol Version 10 to Protocol Version 11 and clearing a path for the Ouroboros Leios scalability upgrade targeted for late 2026. Onchain data from Cardanoscan shows the protocol version change occurred in epoch 644, following epoch 643 under Version 10.

The upgrade introduces Plutus improvements and Plutus Cost Model enhancements intended to lower smart contract execution costs on the network, according to a weekly development report published Friday by Input Output, the engineering company that designed and built the Cardano blockchain. Input Output wrote: "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, designed to increase transactions per second without weakening the protocol's security guarantees. The Dijkstra hard fork that will follow van Rossem is the planned vehicle for introducing Leios to mainnet, with a target launch window of late 2026.

The van Rossem activation also marks a structural shift in how Cardano upgrades are coordinated. It is the first governance-driven hard fork in the network's history, distinguishing it from prior upgrades that were coordinated directly by Input Output. The Cardano Foundation separately canceled its annual conference earlier this cycle after a failed funding vote, a separate matter from the technical rollout.

No changes to $ADA tokenomics or consensus security parameters were announced as part of the van Rossem activation, and Input Output's report framed the upgrade strictly as a foundation for subsequent work rather than the scalability leap itself.