服务器一直报错

07.09 21:16:38 [Server] WARN at AsyncPacketThread.run(AsyncPacketThread.java:20)
07.09 21:16:38 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;
07.09 21:16:31 [Server] INFO 当前有 0 个玩家在线,最大在线人数为 30 个玩家.
07.09 21:16:29 [Server] WARN at AsyncPacketThread.run(AsyncPacketThread.java:20)
07.09 21:16:29 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;
07.09 21:16:20 [Server] WARN at AsyncPacketThread.run(AsyncPacketThread.java:20)
07.09 21:16:20 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;
07.09 21:16:11 [Server] WARN at AsyncPacketThread.run(AsyncPacketThread.java:20)
07.09 21:16:11 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;
07.09 21:16:02 [Server] WARN at AsyncPacketThread.run(AsyncPacketThread.java:20)
07.09 21:16:02 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;
07.09 21:15:59 [Server] INFO 当前有 0 个玩家在线,最大在线人数为 30 个玩家.
07.09 21:15:53 [Server] WARN at AsyncPacketThread.run(AsyncPacketThread.java:20)
07.09 21:15:53 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;
07.09 21:15:44 [Server] WARN at AsyncPacketThread.run(AsyncPacketThread.java:20)
07.09 21:15:44 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;
07.09 21:15:35 [Server] WARN at AsyncPacketThread.run(AsyncPacketThread.java:20)
07.09 21:15:35 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;