Cardano Leios Update Requires Musashi Testnet Restart

Input Output’s latest Leios pre-release requires the Musashi Dojo testnet to restart because its endorser-block format is incompatible with earlier versions. The update arrives during Fire, the phase testing how Cardano’s proposed throughput upgrade behaves under increasing load.

New Leios Block Format Breaks Compatibility

Ouroboros Leios expands Cardano’s transaction capacity through additional endorser blocks alongside the existing Praos chain. These reference transactions that a committee of stake pools validates and votes on. A certificate allows those transactions to enter the ledger.

The design provides additional capacity for ADA transfers and application transactions. Endorser blocks use separate distribution and validation processes, requiring participating nodes to follow compatible communication rules.

A node running rc-2026w42 cannot exchange endorser blocks with earlier versions or read their chains. According to the release notes, operators must delete both the local chain database and Leios databases before synchronizing the restarted network from genesis.

Certification Moves One Slot Earlier

Block producers can now certify an endorser block immediately after the required announcement, voting, and diffusion periods have elapsed. With the default parameters, that becomes possible after 14 slots, one slot earlier than in previous releases.

The change aligns the prototype with CIP-164 and the upstream node’s header-validation rules. The threshold defines the earliest permitted certificate inclusion; actual inclusion also depends on the production of an eligible block.

Certification across an epoch boundary is now prohibited. Nodes reject headers attempting to certify an endorser block announced in the previous epoch, and block producers no longer create such certificates.

The release also fixes a prototype bug that could allow a transaction with a failing Plutus script to spend its script-locked inputs after its endorser block was certified. The correction preserves the script-validity flag in the transmitted transaction encoding. It also requires fresh validation when the protocol version used for voting differs from the version under which the transaction was previously checked.

Musashi Fire Tests Cardano’s Initial Parameters

Musashi Dojo is operated by Input Output, with independent stake pool operators running Leios-enabled block producers and participating in consensus. Test ADA and delegation support their involvement.

During Fire, traffic increases progressively to establish sustainable operating levels, expose software problems, and evaluate protocol settings. The testnet also gives application teams an environment to check wallets, indexers, and other tools against Leios.

Intersect’s October 17 update reported that Musashi exceeded Preview and Preprod in network size and geographic distribution. The development team held two open sessions during testing on October 15, with findings expected to inform the initial parameter settings for Cardano mainnet.

Operators also gain a new cardano-cli query leios-committee command for inspecting the voting committees of the current and next epoch.

Committee information previously returned by query stake-snapshot moves to that dedicated query, accompanying the release’s changes to certification timing and epoch boundaries.