Custom resource pack languages prevent me from joining servers.

My custom resource pack adds another language and changes game textures. Everything works in order until I use the new language while joining my server which is using the server jar provided for 15w34a. I instantly get disconnected on join until I change the language back. Also, if I stop using my resource pack and the custom language is not in the languages list, the join server then instant disconnect bug persists until I change the language again.