Fantom Kittens HD mid-minting post-mortem
Problem: Minting was broken due to an upgrade in the DAO safe contract.
What was happening and how did it happen:
When minting we forward the minting money to the DAO address (0xC748E6dE30222F4e9bC01812860FF005A82543E) which is a Gnosis Safe contract.
Recently Gnosis released an update to the safe which changed the behavior when receiving new ETH/Fantom into the account leading to a higher gas consumption. We were using address.transfer method to forward the minting money to the safe which applies a hard limit of 2300 gas units to the transfer which caused the transaction to revert because upon receiving the money the DAO safe contract was emitting a new event which causes the high gas consumption.
I had some suspicions about what was the culprit initially but it was taking hours to properly debug and validate them — like that someone had mistakenly removed the minter contract permissions to mint and etc. But then Marco Worms reminded me of Tenderly and it was then just a matter of plugging in the transaction in a forked simulation and in less than 5 minutes I could confirm everything!
The solution: I deployed a new minter contract that uses a direct transfer method without hard capping the gas consumption of the transfer method.
Join the Kittens at https://discord.gg/nAkU5Tu3DE
