When leading a channel off of a container, the game crashes if you try to set it to flowing down without another channel underneath of it. I tested this several times and it happens with both terracotta and porcelain versions. This also happens when shift clicking instead of placing the channel underneath of it.

Crash report or it didn't happen. In other words, never crashed for me.

crash-2021-02-11_20.09.25-client.txt

I'm new to GitHub (this is my first post) so I hope I'm following protocol by adding to this topic instead of starting a new one. I'm having the same crashing problem exactly which is a shame because I love the water channels. I am using the latest Valhelsia 3 (3.1.9) modpack and added Ceramics with Mantle so I knew I was pushing my luck. I've added a few other mods to Val 3 without any problems, but others don't work out as well - it's hit and miss. I have not tried running an instance (via MultiMC) of Ceramics without any other mods, so I can't say it's a problem with Ceramics or one of the other 200+ mods in Val 3! Here's my crash report. Love your mod, I'm making a much smaller modpack and I'm betting Ceramics will work fine there. Thank you for taking the time to create this!

crash-2021-03-10_09.33.32-client.txt

I don't think this is a modpack problem. This crash report looks like one of those where I wonder why it never happened in testing. I just have not had time to fix it yet.

Fixed in 1.6.2. For the record, this crash is from right clicking the bottom of a block with a channel. Not related to adjusting connections, you just were trying to do that when the game interpreted you wanting to place the block.