Bukkit

Hey, this is what i get :

[23:56:49] [Craft Scheduler Thread - 138/WARN]: org.apache.commons.lang.UnhandledException: Plugin GAListener v1.3.2 generated an exception while executing task 42
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
at org.github.paperspigot.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:23)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NoSuchMethodError: org.bukkit.Server._INVALID_getOnlinePlayers()[Lorg/bukkit/entity/Player;
at com.swifteh.GAL.Metrics.postPlugin(Metrics.java:335)
at com.swifteh.GAL.Metrics.access$4(Metrics.java:328)
at com.swifteh.GAL.Metrics$1.run(Metrics.java:223)
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:59)
at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
... 4 more