Disconnected for "Server sent invalid player data"

After the update to 1.7.8 my players started getting kicked with this message. The server log doesn't show anything but the usual message:

hivemined lost connection: TextComponent{text='Disconnected', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null}}