What is the output link of /viaversion dump?

https://gist.github.com/7c51070a06ad80aa395e915575bf67fa

Are you using any additional software like BungeeCord? If so, what software and version? (Please list your plugins as well)

No, I'm not use BungeeCord

Plugins: Viaversion, ViaBackwards ans ViaRewind

How does this error happen? login? Using an item?

Items in villager GUI ( http://prntscr.com/i20ltw )

Is there an error in the console? Use pastebin.com. Is there a kick message?

No. It work in 1.8 but it doesn't work in 1.7

Thanks for reporting this bug. I will have a look at it.

fixed