It adds new features to Plutus, the platform used by developers to write Cardano’s smart contracts, unifying the built-in functions available across all three versions of the platform so that older applications benefit from newer features.
The upgrade also strengthens several ledger validation rules, including one ensuring that no stake pool can reuse the same cryptographic identity key.
“In addition to the improvements to Plutus and the Plutus cost model, this upgrade lays the foundation for the next upgrade, the Dijkstra era hard fork, which will introduce Ouroboros Leios to Cardano,” Input Output wrote in a development report on Friday.
Ouroboros Leios is a scaling proposal for the proof-of-stake consensus model run by Cardano. It is expected later in 2026 and aims to sharply increase transactions per second without weakening the protocol’s security guarantees.
Van Rossem is the procedural basis of Ouroboros, both in the ledger changes he makes and the precedent he sets: that Cardano can now improve through voting.
The hard fork is named after Max van Rossem, a contributor to Cardano’s governance who helped shape the network’s constitution and died in October 2025.
What the hard fork means for a Cardano user
There is no visible change to someone who casually holds or spends ADA. Transactions work the same, wallets do not need to be updated, and fees for sending ADA remain unchanged. The upgrade does not change the look or feel of using the network.
