Kusama Runtime Upgrade to 1.2.2

This proposal aims to upgrade Kusama to the lastest release (1.2.2): aiming to fix some issues encountered with core sales and bridges.

When Kusama upgraded to the 1.2.0 runtime it migrated itself to Coretime. This migration is done by iterating the current state of parachains and sending this information to the Coretime chain using multiple Xcm messages. One of these Xcm messages is setting up the leases to match the leases of the old auction model (this should ensure that parachains that won leases using the old auction model still get Coretime until the end of their lease). However, this Xcm message failed to execute because of a Weight mismatch (the third message.Processed event here showing success false). Basically this means that the message announced would use less weight than what it would actually use and this made the Xcm message fail. This is a security measurement to ensure that Xcm messages cannot stall a chain.

For this reason, a runtime upgrade is proposed that reruns the Xcm message, but also includes a fix that ensures that every parachain that had a lease before core sales start can renew their core. The side effect of this runtime upgrade is that the sales state is reset, meaning that the sales start 7 days after this runtime upgrade is applied.

Changes on Kusama BridgeHub 1.2.2 upgrade

The Polkadot-GRANDPA-light-client running on Kusama BH doesn’t correctly handle a corner case involving validator set changes following validator slashing. As a result of the bug, the GRANDPA light-client can fail to recognise the other side's validator set change and thus start refusing to accept subsequent validator set changes as well. More details can be found on this forum post.


We have encountered this bug on the Polkadot BH, resulting in Kusama->Polkadot traffic being stuck. This upgrade fixes the bug for Kusama BH so that it is protected from encountering the same issue.

Please note this proposal is submitted on Whitelisted Caller track - a parallel submission is up for vote on Fellowship to whitelist this proposal.