Forge version: forge- 14.23.1.2589
Botania version: 352
Link to crash log:
https://pastebin.com/868uzNeT

Modpack in use:
https://minecraft.curseforge.com/projects/shavercraft

Steps to reproduce:

1. Just take a Botania flying device [The tiara's], open baubles, and place on the helmet.

What I expected to happen:
Just to be able to fly
What happened instead:
Server won't let me back on unless I delete my player file

I only get kicked with a internal server error,

Similar issue, single player with same version, Terrasteel Equipment + Greater Mana Ring. Put ring on, instant game crash, and continues to crash every load-in.

Edit: @Toapoint The newest version of baubles causes this issue, seems to be something they changed in the API. If you want to get your character back, suggest reverting baubles to 1.5.1 until a fix is implemented.

Reproduced in Natural Pledge dev environment.

Same as #2509, downgrade baubles as a temporary workaround