Cardano developers have finalized the scope of the network’s upcoming Dijkstra era, setting out a two-phase upgrade that will first deploy Ouroboros Linear Leios and Nested Transactions before introducing the Peras consensus enhancement through a separate hard fork in 2027. Intersect, the Cardano ecosystem organization coordinating the upgrade process, confirmed in its latest development update that the scope and target schedule remain intact after the first Dijkstra hard fork was frozen following review by its Technical Steering Committee.
Phase 1 is targeting the fourth quarter of 2026 and will establish the Dijkstra ledger era while activating Linear Leios. Phase 2 is expected in the second quarter of 2027 and will activate Ouroboros Peras through an intra-era hard fork. The dates remain targets rather than guarantees, with testing, ecosystem readiness and Cardano’s on-chain governance process potentially affecting deployment.
Leios Targets a Major Increase in Throughput
Linear Leios represents the principal scaling component of Dijkstra’s first phase. Cardano currently relies on Ouroboros Praos for its underlying consensus security. Leios is designed to substantially increase the amount of transaction data the network can process without abandoning those existing security assumptions. The architecture introduces additional block structures, including Endorser Blocks, allowing more transactions to be processed and subsequently certified through stake-based committees rather than forcing all activity through the existing block-production bottleneck. Input Output has previously said it is targeting an initial fivefold to 20-fold increase in Cardano’s base-layer throughput capacity through Leios.
Phase 1 will also introduce Nested Transactions and several additional ledger changes, including new transaction and block serialization structures, protocol parameters and Plutus V4-related functionality. Importantly, the first upgrade will install the codecs and parameters necessary for Peras without activating the protocol itself. That allows developers to prepare the ledger foundation for the second phase while avoiding the complexity of deploying both major consensus changes simultaneously.
Peras Targets Faster Cardano Settlement
Peras addresses a different scaling constraint. Rather than primarily increasing transaction throughput, Ouroboros Peras is designed to improve settlement speed by introducing stake-based voting on recent chain tips. Committees of stake pool operators can endorse the preferred chain, allowing transactions to achieve stronger settlement assurances faster than relying exclusively on Praos chain-depth rules. Intersect currently targets Q2 2027 for Peras activation.
The second deployment will be an intra-era hard fork, meaning Cardano will remain within the Dijkstra ledger era while its protocol version changes to activate Peras. Preview and Pre-production testnet deployments and another mainnet governance action are expected before activation. Dijkstra is also coinciding with efforts to diversify Cardano’s node infrastructure. Amaru, an open-source Cardano node implementation written in Rust, can already validate the blockchain and synchronize to its tip. Developers are targeting mainnet block-production capability during November 2026. That could reduce Cardano’s dependence on its established Haskell node implementation while providing another independent implementation against which protocol behavior can be tested. Taken together, the staged Dijkstra roadmap separates two of Cardano’s most ambitious protocol improvements into distinct engineering problems: Leios is intended to dramatically expand how much activity the blockchain can process, while Peras is intended to make that activity settle faster.
If both reach mainnet on schedule, 2026 and 2027 could represent one of the largest changes to Cardano’s base-layer architecture since the network introduced smart-contract functionality.