Cardano outlines two-phase Dijkstra upgrade for 2026 and 2027

Cardano will roll out its Dijkstra era upgrade in two stages, beginning with a Q4 2026 hard fork that activates Ouroboros Linear Leios and followed by a Q2 2027 upgrade to activate Ouroboros Peras.

The first phase will introduce Dijkstra as a new ledger era under Protocol Version 12, allowing Cardano to deploy new block structures, serialization changes and protocol parameters required by both Leios and Peras. Peras will then be switched on through an intra-era hard fork because its underlying codec extensions and parameters will already be in place.

The headline feature of Phase 1, Linear Leios, aims to boost network throughput by allowing block producers to publish supplementary Endorser Blocks alongside existing Praos Ranking Blocks. Endorser Blocks reference additional transactions, which are certified by a stake-based committee before being included in the ledger.

The upgrade is intended to increase transaction capacity without requiring larger regular blocks or faster block production.

Dijkstra will also include Nested Transactions, a new script type for transaction validity observation, Phase 1 account address improvements, PlutusV4 script context changes, updated transaction serialization, reference-script pricing and limits, and changes to staking reward withdrawals.

Both phases will follow the same rollout path of Preview testnet, Pre-production testnet and Mainnet, with governance actions required before each hard fork.

Cardano said the Q4 2026 and Q2 2027 dates are estimated code-completion and mainnet-ready targets and do not include testing, governance or community approval timelines.