Minecraft v1.16.5
Forge v36.0.7
Quark r2.4-302

I get this error when trying to connect to my server. Version 300 didn't have this issue.
Error Log

Hello! Quark's moved to 1.18 now-- unfortunately, this means that (unless your bug is critical and/or game-breaking), we're closing support for issues filed for versions prior to it (e.g. Quark on 1.16).

If your issue still occurs on 1.18, or if your issue happens to be rather critical (e.g. consistently crashing the game with no other mods present), please leave another note or open a new issue. Thanks for your cooperation!

Similar Issue, running:

Minecraft v1.16.5
Forge v36.0.15
QuarkOddities-1.16.3
Quark-r2.4-304

(As part of the Valhelsia 3 modpack v3.1.8a)

Similar IllegalStateException but in reference to shulker boxes.

Having the same issue! Was able to play just fine yesterday when I set up the server, but now I can't access it.

Same issue here. We have been playing fine (Valhelsia3) for over a week now. Occured just now randomly.

I'm also having the same issue! I didn't make the seed pouch, I'm using the backpack from quark... also the botania seed pouch and the toolbelt from tetra... unsure if any of that helps.