Version

Ouroboros

Guard

Cardano

Major

Cardano has laid out a two-phase plan for its next major protocol upgrade, known as the Dijkstra era, with the first milestone targeting code completion in Q4 2026 and the second scheduled for Q2 2027.
<h2 id="phase-one-linear-leios-and-nested-transactions">Phase One: Linear Leios and Nested Transactions</h2>
The first phase centers on activating Ouroboros Linear Leios, a next-generation consensus protocol designed to significantly increase the network's base-layer throughput. It does this through supplementary Endorser Blocks, which allow more transactions to be processed in parallel without compromising security or decentralization.
Alongside Leios, Phase One will also introduce nested transactions, which allow transactions to be bundled within one another to optimize resource usage and reduce network load. Guard scripts and improved account addresses are also part of the Phase One scope. The Haskell node team is aiming to deliver Phase One, covering Nested Transactions and Linear Leios, to Cardano Mainnet by the end of 2026.
<h2 id="phase-two-ouroboros-peras-and-faster-finality">Phase Two: Ouroboros Peras and Faster Finality</h2>
Phase Two will activate Peras through an intra-era hard fork scheduled for Q2 2027. Peras will enhance transaction finality by speeding up the time required for a transaction to be considered irreversible.
Neither phase will go live automatically. Both must clear rigorous testing and pass on-chain governance before mainnet activation. This staggered approach is designed to incrementally unlock new capabilities and ensure network stability throughout the evolution of the protocol.
The governance dimension is meaningful. Because upgrades such as Ouroboros Leios will introduce new updatable protocol parameters, Cardano's constitution requires those parameters to be explicitly included in governance guardrails before they can be changed through on-chain processes. Voting has already commenced on a new parameter update, alongside the ongoing on-chain Constitutional Committee election, and community members now have access to the Constitutional Amendment Portal, which has entered alpha testing.
The Dijkstra era follows the van Rossem upgrade, which went live in July 2026. The van Rossem intra-era hard fork shifted the network to Protocol Version 11 and delivered improvements to Plutus performance, ledger consistency, and node security, forming the technical base for the Dijkstra rollout ahead.
Sources: <a href="https://u.today/cardano-prepares-major-node-changes-as-dijkstra-era-takes-shape" rel="noopener noreferrer nofollow">U.Today: Cardano Prepares Major Node Changes as Dijkstra Era Takes Shape</a> <a href="https://en.coinotag.com/cardano-ada-dijkstra-hard-fork-phase-1-end-2026" rel="noopener noreferrer nofollow">CoinOtag: Cardano Keeps Dijkstra Hard Fork Phase 1 on Track for End-2026</a> <a href="https://beincrypto.com/cardano-ada-rally-dijkstra-era-preparations/" rel="noopener noreferrer nofollow">BeInCrypto: ADA Price Jumps 10% While Cardano Turns Toward Its Next Big Upgrade Era</a>

Cardano Plans Major Two Phase Dijkstra Upgrade

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