Console Error On Startup

20.01 22:02:25 [Server] WARN Plugin ChestShop v3.8.12 generated an exception while executing task 159 20.01 22:02:25 [Server] INFO java.lang.NoSuchMethodError: org.bukkit.Server._INVALID_getOnlinePlayers()[Lorg/bukkit/entity/Player; 20.01 22:02:25 [Server] INFO at com.Acrobot.ChestShop.Metrics.postPlugin(Metrics.java:335) ~[ChestShop-Fixed.jar:?] 20.01 22:02:25 [Server] INFO at com.Acrobot.ChestShop.Metrics.access$400(Metrics.java:57) ~[ChestShop-Fixed.jar:?] 20.01 22:02:25 [Server] INFO at com.Acrobot.ChestShop.Metrics$1.run(Metrics.java:223) ~[ChestShop-Fixed.jar:?] 20.01 22:02:25 [Server] INFO at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:71) ~[custom.jar:git-Spigot-9b8bba4-bdcc7c7] 20.01 22:02:25 [Server] INFO at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) [custom.jar:git-Spigot-9b8bba4-bdcc7c7] 20.01 22:02:25 [Server] INFO at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0_131] 20.01 22:02:25 [Server] INFO at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0_131] 20.01 22:02:25 [Server] INFO at java.lang.Thread.run(Unknown Source) [?:1.8.0_131]