TLDR:
- Cardano targets Q4 2026 for Dijkstra Phase 1, introducing Linear Leios and new ledger features.
- Dijkstra Phase 1 will increase throughput through supplementary Endorser Blocks and certification.
- Ouroboros Peras is planned for Q2 2027 to accelerate settlement through stake-pool voting.
- Both phases require testnet deployments and governance approval before mainnet activation.
Cardano plans a two-phase Dijkstra upgrade, with the first stage targeting Q4 2026 code completion and the second planned for Q2 2027.
The rollout will introduce Ouroboros Linear Leios and later activate Ouroboros Peras. Phase 1 will also bring nested transactions, guard scripts, account-address improvements, and other ledger changes.
Phase 2 will focus on faster settlement through a stake-pool voting layer. Both stages require testing and on-chain governance approval before mainnet activation.
Cardano Sets Q4 2026 Target for Dijkstra Phase 1
Cardano’s first Dijkstra phase will establish a new ledger era under Protocol Version 12. The upgrade will activate Ouroboros Linear Leios while preparing the network for Peras.
Code completion is targeted for Q4 2026, although the date does not represent final mainnet activation.
Linear Leios will increase throughput through supplementary Endorser Blocks alongside existing Praos Ranking Blocks.
These Endorser Blocks reference additional transactions that the network can process after certification. As a result, Cardano can increase transaction capacity without relying on larger blocks or faster slots.
A stake-based committee will certify Endorser Blocks through aggregated signatures. The certification requires a 75% quorum of active stake before endorsed transactions enter the ledger.
If no certified Endorser Block exists, Ranking Blocks continue processing transactions through the standard Praos approach.
Phase 1 will also introduce the structural changes required for Peras. These include codec extensions and protocol parameters that cannot be added during an intra-era hard fork. Therefore, the Dijkstra era provides the foundation needed for Peras activation during the second phase.
Dijkstra Adds New Transaction and Ledger Features
The first phase will introduce several changes beyond Linear Leios. Nested transactions will allow transactions to contain child transactions with independent witnesses and execution contexts. This provides additional flexibility for on-chain applications and more expressive transaction structures.
Dijkstra will also introduce guard scripts capable of observing transaction validity without executing as part of spending or minting. The change supports transaction guards and serves as a dependency for the PlutusV4 script context.
Account-address improvements will establish ledger-level definitions for account-style addresses. Meanwhile, the upgrade will remove the isValid field from transactions and introduce non-segregated block body serialization. These changes support the updated ledger and transaction structures.
Cardano will also simplify staking reward withdrawals by removing the DRep delegation requirement. In addition, pledge leverage-based staking rewards will introduce a leverage parameter. However, its default setting preserves current reward behavior until governance chooses another value.
Peras Activation Planned for Cardano in Q2 2027
The second Dijkstra phase is targeted for Q2 2027 and will activate Ouroboros Peras. Unlike Phase 1, this change will use an intra-era hard fork within Dijkstra. No new ledger era will therefore be required for the activation.
Peras will add a voting overlay to the existing Ouroboros Praos chain selection mechanism. Stake-pool committees will vote on recent chain tips, allowing sufficiently supported tips to reach settlement sooner. The protocol will not change how blocks are produced.
Both Dijkstra phases will follow Preview and Pre-production testnet deployments. Phase 1 includes operator testing, Endorser Block propagation checks, integration validation, and throughput benchmarking. Phase 2 will include testing focused on voting and settlement latency.
Mainnet activation will require governance ratification involving DReps, stake pool operators, and the Constitutional Committee.
The published Q4 2026 and Q2 2027 targets remain estimates for code completion and readiness. Actual hard fork dates will depend on testing, governance, and network readiness.
