Bungee 1.7.9 Problem, need help :(

Every time i try to join the server there's this error : Internal Exception: java.lang.ClassCastException: bll cannot be cast to fv
with this error on bungee(but it's running fine):
01:25:45 [WARNING] Plugin performed restricted action, please inform them to use proper API methods: Illegal thread group access
java.security.AccessControlException: Plugin violation: Illegal thread group access
at net.md_5.bungee.BungeeSecurityManager.checkRestricted(BungeeSecurityManager.java:39)
at...

Bungee 1.7.9 Problem, need help