Revive clients after IBC-client-breaking upgrade

[kienvc]

Hello, I have a question about upgrade IBC clients.
I did a hard fork to change chain-id by exporting latest state and using it as genesis
But failed to plan the IBC upgrade correctly.
Now the chain is running with new chain-id, but counterparty IBC clients still have the old one.
Is anyway to revive or upgrade them to correct chain-id?
Thank you!

[srdtrk]

Recovering your IBC clients should be straightforward as long as you can get a governance proposal passed on the counterparty chain, especially if the only significant change in your chain parameters is the chain-id. Here’s a step-by-step guide on how to do this:

Assume the broken counterparty light client has the ID 07-tendermint-1. Follow these steps:

1. Create a New Light Client: Set up a new light client on the counterparty chain with the correct chain-id. Let’s call this new client 07-tendermint-2.
2. Submit a Governance Proposal: On the counterparty chain, create a governance proposal using MsgRecoverClient. Ensure the following parameters are set:
   • SubjectClientId = 07-tendermint-1
   • SubstituteClientId = 07-tendermint-2
   • Signer = governance module address
3. Update the New Client: Continue updating 07-tendermint-2 with a relayer until the proposal passes to prevent it from expiring.
4. Finalize the Process: Once the proposal passes, your original client 07-tendermint-1 will be recovered. You can now relay using 07-tendermint-1 and no longer rely on 07-tendermint-2 (so you can let 07-tendermint-2 expire).

If you need further assistance, feel free to ask!

[kienvc]

Thank you, don't know MsgRecoverClient can update chain-id, thought it only updates latest_height.