It's not a bug, it's a feature. Obviously you have a cauldron above the chest that leaked because it was too small, and the game was nice enough to let you know. Actual response: It looks like it's some sort of issue with craftbook. I'll see if anything comes up on google.
I was getting a similar error when using water buckets to place water above lava. Pieman did tweak something in the CraftBook settings to fix it but it reoccurred a few days later. I haven't been mining obsidian lately so can't say if it is still an issue in that context.
Sounds like we have legacy craftbook cauldrons enabled for some reason. I don't have access to the config files, so I'm not positive, but it seems to be the most likely cause. ndvenckus1 CyberVic sharqman
If I recall correctly I believe Pieman said it was a side effect of custom crafting experiments. Yeah that makes sense. I guess I accidently made a cauldron when I was mining the obsidian and I'm guessing there may be lava beneath that obsidian Slebert has his chest on?
It's disabled in the config. I'll update craftbook, but no promises, it might be an issue fixed in one of the uuid updates of the plugin which we can't use yet.