Cardano's Dijkstra Upgrade On Track for 2026–2027 Rollout

Cardano’s long-awaited Dijkstra upgrade is staying on course — but developers are shifting gears from pure engineering to ecosystem readiness as they prepare a two-phase rollout that spans 2026–2027. What’s coming and when - Phase 1: Dijkstra ledger era with Linear Leios (the main scaling feature), Nested Transactions, new transaction/block serialization, Plutus V4 updates and several protocol-parameter additions. Intersect targets code completion in Q4 2026. Phase 1 will also install the codec extensions and parameter slots required for the next phase, but it will not activate Ouroboros Peras. - Phase 2: Ouroboros Peras, which adds an on-chain voting layer of stake-pool operator committees to accelerate settlement versus standard Praos chain-depth rules. Peras is planned as an intra-era hard fork targeted for Q2 2027 and will require its own preview, pre-production deployments and a separate on-chain governance action. Key technical details - Linear Leios does not replace Cardano’s Praos security model. Instead it introduces “Endorser Blocks” that can reference and certify additional transactions via stake-based committees — a design intended to boost throughput while preserving the base consensus guarantees. - Nested Transactions and codec/serialization updates in Phase 1 prepare the ledger for Peras without switching it on immediately. - The van Rossem hard fork in July moved mainnet to Protocol Version 11 and laid foundational groundwork for Dijkstra and Leios. Node diversity and Amaru (Rust node) - Intersect highlights a push for greater node-client diversity. Amaru, an open-source Rust node, is already capable as a relay and can validate and sync to the chain tip. Mainnet block production for Amaru is targeted for November 2026, with development milestones shown as: general block-producer release (Sept. 30), Dijkstra-compatible block producer milestone (Oct. 29) and Leios-compatible release (Nov. 26). These are development targets rather than guaranteed activation dates. - Increasing alternative node implementations aims to reduce reliance on the Haskell node and broaden the ecosystem. Governance and constitutional changes - Some Dijkstra protocol parameters can’t be altered by on-chain governance unless they’re explicitly covered by the Constitution’s guardrails. Input Output plans a narrowly scoped constitutional amendment that adds those parameters and permitted ranges — without changing governance roles, voting thresholds or constitutional principles. - The current plan is to submit that governance action no later than Epoch 655 (beginning Sept. 11). Community discussion is being funneled through Intersect’s Constitutional Amendment Portal, which had four initial submissions as of Aug. 14. Process and caveats - Intersect’s Aug. 14 Weekly Update (#124) says planning is shifting toward testnet reporting, ecosystem readiness and support for alternative node teams, and that the agreed technical scope and target dates remain unchanged. - The roadmap’s Q4 2026 (Phase 1 code-completion) and Q2 2027 (Peras activation) targets are estimates, not guarantees. Testing, preview/pre-production cycles and on-chain governance can push mainnet activation later. Why it matters If successful, Dijkstra’s Linear Leios and Peras together could materially increase Cardano’s throughput and settlement speed while keeping existing consensus guarantees intact. The timeline also signals a maturation of the ecosystem — from a single Haskell reference node to a more diverse, multi-client network — and a careful governance path for sensitive protocol changes. Bottom line: developers are on schedule to deliver Phase 1 features in 2026 and to pursue Peras in 2027, but community testing, node diversity efforts and governance actions will determine the final mainnet dates.