Any idea what this means?

[19:59:59 WARN]: Exception in thread "Craft Scheduler Thread - 60"
[19:59:59 WARN]: org.apache.commons.lang.UnhandledException: Plugin Multiverse-Core v2.5-b688 generated an exception while executing task 24
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
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.getOnlinePlayers()[Lorg/bukkit/entity/Player;
at org.mcstats.multiverse.Metrics.postPlugin(Metrics.java:357)
at org.mcstats.multiverse.Metrics.access$400(Metrics.java:64)
at org.mcstats.multiverse.Metrics$1.run(Metrics.java:245)
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftTask.run(CraftTask.java:71)
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
... 3 more

[20:10:01 WARN]: Exception in thread "Craft Scheduler Thread - 69"
[20:10:01 WARN]: org.apache.commons.lang.UnhandledException: Plugin Multiverse-Core v2.5-b688 generated an exception while executing task 24
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
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.getOnlinePlayers()[Lorg/bukkit/entity/Player;
at org.mcstats.multiverse.Metrics.postPlugin(Metrics.java:357)
at org.mcstats.multiverse.Metrics.access$400(Metrics.java:64)
at org.mcstats.multiverse.Metrics$1.run(Metrics.java:245)
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftTask.run(CraftTask.java:71)
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
... 3 more

[20:20:03 WARN]: Exception in thread "Craft Scheduler Thread - 77"
[20:20:03 WARN]: org.apache.commons.lang.UnhandledException: Plugin Multiverse-Core v2.5-b688 generated an exception while executing task 24
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
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.getOnlinePlayers()[Lorg/bukkit/entity/Player;
at org.mcstats.multiverse.Metrics.postPlugin(Metrics.java:357)
at org.mcstats.multiverse.Metrics.access$400(Metrics.java:64)
at org.mcstats.multiverse.Metrics$1.run(Metrics.java:245)
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftTask.run(CraftTask.java:71)
at org.bukkit.craftbukkit.v1_10_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
... 3 more