Plugin Help invalid inventory size fix?

title pretty much explains the issue, my server uses Essentials trade signs and i haven't yet found a fix looking through various online forums, i'm not able to currently get on my server working out of town, but does it just require updating essentials?

chat error: Error: invalid inventory size, expected 36 or less

Server is 1.9 snapshot. there don't appear to be any other issues. op/rank makes no difference, so i imagine it's the plugin.