Board Thread:Bug Reports/@comment-29716003-20160826010216

I have a new LOTR server in development and one of my admins is having issues connecting, when he trys joining he gets this, java.lang.StringIndexOutOfBoundsException: String Index out of range: -1. I asked about it on the bug forums for minecraft itself and they found this in my servers logs  iIllegal extra prefix item.lotr for name item.lotr:morgulBlade, invalid registry invocation/invalid name?, thinking it might be the cause help would be great, thanks  