3.0.0 also made my players crash. just trying to move an item from box. going back to 2.0.4. good luck with the fix!

(Kicked: RPC Error in MoveItem)

when i move water from small water bottle to water jug

This issue should be resolved in v3.1.1. If you encounter the issue again let me know.

still not fixed..and when i reload the plugin It multiplies the stacks x2 again and again...i download again v2.0.4

You have another plugin conflicting with StackSizeController. Do you have any others interacting with inventories, chests or stack sizes? Do you have ChestStacks? Trying to figure out which plugin is doing it, so I can tell that developer to fix their implementation.

i send u private message

This problem still happens today