Don't know how to fix this, driving me nuts on my server. I have a pretty simple server with 100 plugins. When I drag random items from my inventory to backpack or from backpack back to my inventory or box to my inventory I get this error, once it happened on leather, now it happened on timed explosives.

I reload the stack plugin, loot plugin, restart server, still error persists and I get kicked immediately when this error occurs.

AssertionException: Assertion failure.
Value was False Expected:
True split_Amount <= 0

If I delete the StackSizeController json and start over with my settings it works again, then eventually random items will start doing this again.

Merged post

Yep, have to really watch the category multipliers and individual multipliers, they "stack" together, I had explosives set to 10 000 and resources to 1 000 000. I didn't think that explosives was a resource and it ended up stacking that item to 10 000 000 000 which is bigger than max int that the variable can store 2147483647 to -2147483648 to it was rolling over and ending up in the -ve side of the int variable. Thus the True split_Amount <= 0 error.

NOOB!