Troubleshooting

🟥 Known Critical Bug: Hydra Head Close Fails on Conway/Protocol 10.x

Summary:
After opening and funding a Hydra Head with latest Hydra (1.2.0) and Cardano node (10.1.4, Conway/protocol 10.x), the head cannot be closed. Attempting to close ({"tag":"Close"}) triggers a PlutusV3 script validation error.

Symptoms:

• Hydra head opens successfully (Init → Commit → CollectCom → Open)
• Any Close action (TUI/API) fails
• Node returns ValidationTagMismatch and Plutus error, e.g.:

  ShelleyTxValidationError ShelleyBasedEraConway (ApplyTxError (ConwayUtxowFailure (UtxoFailure (UtxosFailure (ValidationTagMismatch (IsValid True) (FailedUnexpectedly (PlutusFailure "..."))))))
  

  Hypothesis:
  Protocol compatibility—Hydra 1.2.0 is NOT YET compatible with Cardano protocol 10.x (Conway) on Yaci DevKit.

Workarounds:

• Use Cardano node protocol version 9.x (downgrade your node)
• Check for new Hydra releases
• Export protocol parameters from the node and replace config/hydra/protocol-parameters.json
• See Hydra repo issues

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Other Issues & Resolutions

Cannot Start Node/Bridge

• Ensure npm run start:devnet and the Yaci socket bridge are BOTH running in separate terminals.

Port Conflict

• Use lsof -i :<port> to find and kill process OR change port in config.

“Invalid participant index”

• Ensure you run head/TUI scripts with an index in range (i.e., for 3 participants use 0, 1, or 2).

Permission Issues

• If files in keys/ or bin/ are root-owned, run sudo chown -R $USER:$USER keys/ bin/ logs/

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When in Doubt

• Review shell output!
• Open a GitHub Issue with error log and your protocol version info.