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Version: v8.3.x

Migrating from v8 to v8.1

This guide provides instructions for migrating to version v8.1.0 of ibc-go.

There are four sections based on the four potential user groups of this document:

Note: ibc-go supports golang semantic versioning and therefore all imports must be updated on major version releases.


04-channel params migration

Self-managed params have been added for 04-channel module. The params include the upgrade_timeout that is used in channel upgradability to specify the interval of time during which the counterparty chain must flush all in-flight packets on its end and move to FLUSH_COMPLETE state (see Channel Upgrades for more information). An automatic migration handler is configured in the 04-channel module that sets the default params (with a default upgrade timeout of 10 minutes). The module has a corresponding MsgUpdateParams message with a Params field which can be specified in full to update the module's Params.

Fee migration

In ibc-go v8.1.0 an improved, more efficient escrow calculation of fees for packet incentivisation has been introduced (see this issue for more information). Before v8.1.0 the amount escrowed was (ReckFee + AckFee + TimeoutFee); from ibc-go v8.1.0, the calculation is changed to Max(RecvFee + AckFee, TimeoutFee). In order to guarantee that the correct amount of fees are refunded for packets that are in-flight during the upgrade to ibc-go v8.1.0, an automatic migration handler is configured in the 29-fee module to refund the leftover fees (i.e (ReckFee + AckFee + TimeoutFee) - Max(RecvFee + AckFee, TimeoutFee)) that otherwise would not be refunded when the packet lifecycle completes and the new calculation is used.

IBC apps

  • No relevant changes were made in this release.


  • No relevant changes were made in this release.

IBC light clients

  • No relevant changes were made in this release.