Players are crashing, log says something about users underwater.

https://pastebin.com/5K71HmdP

Thanks for the report, I'll been checking this by the end of the week.

Could reproduce the issue : the game would crash when the capsule is thrown by non-player entity (ex: dropper or dispenser).

This regression was introduced with the water update :

• issue is now fixed in version 1.12.2-3.1.69
• earlier versions are not affected (< 1.12.2-3.1.63)

1.12.2-3.1.69 is currently being uploaded, will close the issue once it is available.

Now available at https://minecraft.curseforge.com/projects/capsule.