Cardano is executing two concurrent protocol upgrades in late June 2026. The Van Rossem hard fork — named for deceased governance contributor Max van Rossem — moves the network to Protocol Version 11, adding five new Plutus primitives including BLS12-381 cryptographic curves for zero-knowledge ap...
"Yes, it will ship in 2026. No if, ands, or buts about it." — Charles Hoskinson, Founder, Input Output Global
Cardano is executing two concurrent protocol upgrades in late June 2026. The Van Rossem hard fork — named for deceased governance contributor Max van Rossem — moves the network to Protocol Version 11, adding five new Plutus primitives including BLS12-381 cryptographic curves for zero-knowledge applications, modular exponentiation (CIP-109), and multi-scalar multiplication (CIP-133). Separately, the Ouroboros Leios public testnet launches June 23, deploying a three-layer block architecture designed to increase throughput 30–65x over current capacity.
The two upgrades serve distinct purposes. Van Rossem is an intra-era hard fork that widens the smart contract toolset and lays groundwork for the Dijkstra era. Leios restructures consensus itself, decoupling transaction inclusion from ordering through parallel Input Blocks, Endorser Blocks, and Ranking Blocks. Together they represent Cardano's most aggressive scaling push since the Shelley transition — arriving while the network's DeFi TVL sits at $91.6M against Ethereum's $28B, a gap exceeding 300x.
The Van Rossem hard fork is Cardano's first protocol upgrade initiated through the Voltaire on-chain governance framework rather than by IOG acting unilaterally. The hard fork initiation governance action was submitted on the Cardano mainnet on June 16, 2026, following ratification of the prerequisite Plutus Cost Model parameter update by DReps and Constitutional Committee members on June 13, with 68.57% DRep approval and 5/7 CC member votes. The cost model update was enacted on June 18 at 21:45 UTC.
The hard fork itself requires 85% of stake pools by active stake to upgrade to Cardano Node version 11.0.1 before ratification can proceed — a constitutional requirement, not a soft target. Potential ratification dates range from June 23 to July 18, 2026, with enactment possible as early as June 28 if approval accumulates quickly.
Protocol Version 11 introduces five Cardano Improvement Proposals:
The BLS12-381 additions are directly connected to IOG's Halo2-Plutus verifier and the Midnight-Cardano zero-knowledge bridge, linking the cryptographic primitives to a visible product roadmap. IOG characterizes the upgrade as delivering "cheaper smart contracts, ZK-ready cryptography, and tighter stake pool security."
The upgrade carries the name of Max van Rossem, a Cardano governance contributor, stake pool operator, DRep, and Constitutional Convention delegate who died on January 11, 2026. An on-chain naming vote in January-February 2026 received 83.62% DRep support with 4.44 billion ADA backing, according to Intersect.
The Ouroboros Leios public testnet is scheduled to launch on June 23, 2026, representing the first live test of a protocol that has accumulated over 5,700 technical updates and 705,000 lines of code, according to reporting by Cryptonomist.
Leios replaces Cardano's monolithic block structure with three specialized block types produced independently across decoupled, pipelined stages:
| Block Type | Function | Frequency | Producer | |---|---|---|---| | Input Blocks (IBs) | Bundle user transactions | Every 0.2–2 seconds | Stake Pool Operators | | Endorser Blocks (EBs) | Validate and aggregate IBs | Every ~5 seconds | Committee members | | Ranking Blocks (RBs) | Finalize ordering and anchor | Every ~20 seconds | Praos consensus |
The core design separates transaction inclusion from ordering. SPOs process multiple IBs in parallel, which are then aggregated into EBs for consensus. RBs provide final ordering using existing Praos security mechanics. According to the Leios specification (CIP-0164), the protocol employs a voting and certificate scheme where committee members cast votes referencing specific EBs, aggregated into compact certificates via BLS signatures for inclusion in RBs.
Early simulations indicate a projected 30–50x throughput increase, from approximately 4.5 TxkB/s to 140–300 TxkB/s. In transaction terms, estimates range from 200 to 1,000 TPS depending on transaction size, with some projections extending to 11,000 TPS under optimistic conditions. For context, Cardano currently processes approximately 250 TPS with 20-second block times.
IOG submitted a treasury proposal for ₳27,714,342 (approximately $4.7M at current ADA prices) to mature Leios from prototype to mainnet-ready release candidate. The proposal passed with approximately 84% DRep approval. The funding covers six to nine months of development through late 2026, with IOG operating what Hoskinson described as "a 24/7 implementation, a follow-the-sun model."
The Van Rossem upgrade provides the most substantive test of Cardano's Voltaire-era governance to date. Under this framework:
The Plutus Cost Model update — a prerequisite for the hard fork — achieved ratification on June 13 with 68.57% DRep approval and 5/7 CC votes. The hard fork initiation action was submitted June 16 and was tracking at approximately 55% DRep approval as of Intersect's June 12 weekly update, with ratification expected within weeks.
This governance sequence is significant beyond Cardano. It demonstrates a functioning on-chain upgrade ratification process where protocol changes require multi-stakeholder consensus across three distinct bodies (DReps, CC, SPOs) before activation. Whether this model proves more resilient or more friction-laden than alternatives (Ethereum's off-chain rough consensus, Solana's foundation-led coordination) remains to be measured by execution speed and outcome quality.
| Metric | Cardano (Current) | Cardano (Post-Leios, Projected) | Ethereum L1 | Ethereum L1 + L2s | Solana | |---|---|---|---|---|---| | TPS | ~250 | 200–1,000+ | 15–20 | 5,000+ aggregate | 600–4,000 | | Block Time | 20s | Variable (0.2–20s by layer) | 12s | Varies | 0.4s | | Finality | ~20s | ~20s (RB layer) | ~12 min (2 epochs) | Varies | ~0.4s | | Scaling Model | Monolithic | Pipelined parallel | Modular (rollups) | Rollup-centric | Monolithic |
Solana's Alpenglow upgrade, separately covered, targets 100–150ms finality, placing it in a different performance class. Ethereum's strategy relies on L2 aggregation rather than L1 throughput. Cardano's Leios approach is distinct: maintaining a single-layer chain while parallelizing block production internally. This preserves the simplicity of a single settlement layer but introduces coordination complexity across three block types.
Hydra, Cardano's off-chain scaling solution, theoretically enables millions of TPS for specific use cases but operates as a separate system from Leios and targets different workloads.
The upgrades arrive during a period of economic weakness for the Cardano ecosystem:
The staking participation rate (67.3%) is among the highest in proof-of-stake networks, reflecting strong holder commitment to network security. However, the DeFi TVL figure — $91.6M — suggests that staking yield, not application usage, drives the majority of on-chain economic activity. The stablecoin base at $45.85M is insufficient to support deep DeFi liquidity pools or meaningful lending markets.
The economic question facing both upgrades is whether technical capability translates to usage. Cardano's current ~250 TPS is not a binding constraint at present utilization levels. The protocol rarely approaches capacity limits. Leios addresses a throughput ceiling that, as of mid-2026, the network does not consistently hit.
Execution Risk: The ₳27.7M treasury allocation funds six to nine months of Leios development. Converting a 705,000-line testnet prototype into mainnet-ready software within that window requires sustained engineering velocity. Hoskinson's "follow-the-sun" model suggests urgency but also acknowledges the timeline is tight.
Governance Friction: The Van Rossem upgrade process — from cost model submission (May 26) to potential hard fork enactment (June 28 at earliest, July 18 deadline) — spans roughly two months. For comparison, Solana's Alpenglow proposal advanced through foundation coordination in weeks. The Voltaire model adds legitimacy but also latency.
Demand Gap: Even at 30–65x throughput, the network needs applications that generate sustained transaction volume. Cardano's DeFi ecosystem, with $91.6M in TVL and a $45.85M stablecoin base, does not currently produce traffic volumes that would test even current capacity limits.
Competition: Ethereum's L2 ecosystem already delivers 5,000+ aggregate TPS. Solana targets sub-second finality. Cardano's Leios, if delivered, would bring the network into the same throughput range but arrives later and into a market where competing chains have already captured liquidity and developer mindshare.
ZK Adoption: The BLS12-381 primitives from Van Rossem enable ZK applications, but developer uptake depends on tooling maturity (Halo2-Plutus verifier) and the Midnight bridge timeline, neither of which has firm mainnet dates.
Cardano's June 2026 upgrade pair addresses two different layers of the protocol stack: Van Rossem expands what smart contracts can do; Leios restructures how the network processes transactions. Neither upgrade, on its own, resolves Cardano's core economic challenge — a DeFi ecosystem that is orders of magnitude smaller than competitors despite years of development.
The technical merit of both proposals is measurable and will be tested. Leios's three-block architecture is architecturally distinct from both Ethereum's rollup model and Solana's monolithic approach. The ZK primitives from Van Rossem connect to a concrete product roadmap through the Midnight bridge. And the Voltaire governance process, while slower than centralized coordination, produces verifiable on-chain consent.
What remains unresolved is whether technical capacity creates demand or merely accommodates it. Cardano's current utilization does not strain its existing ~250 TPS ceiling. The network is building a highway. The open question is whether the traffic follows.