[12:40:20] [Craft Scheduler Thread - 96/WARN]: [WaterFlowLimit] Plugin WaterFlowLimit v1.2.0 generated an exception while executing task 48
java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
        at org.mcstats.Metrics.postPlugin(Metrics.java:335) ~[?:?]
        at org.mcstats.Metrics.access$400(Metrics.java:57) ~[?:?]
        at org.mcstats.Metrics$1.run(Metrics.java:223) ~[?:?]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:76) ~[spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0]



[12:40:20] [Craft Scheduler Thread - 109/WARN]: [CS-CoreLib] Plugin CS-CoreLib vv1.5.18 generated an exception while executing task 59
java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
        at org.mcstats.Metrics.postPlugin(Metrics.java:335) ~[?:?]
        at org.mcstats.Metrics.access$400(Metrics.java:57) ~[?:?]
        at org.mcstats.Metrics$1.run(Metrics.java:223) ~[?:?]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:76) ~[spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0]



[12:40:20] [Craft Scheduler Thread - 114/WARN]: [ExoticGarden] Plugin ExoticGarden v1.6.3 generated an exception while executing task 195
java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
        at org.mcstats.Metrics.postPlugin(Metrics.java:335) ~[?:?]
        at org.mcstats.Metrics.access$400(Metrics.java:57) ~[?:?]
        at org.mcstats.Metrics$1.run(Metrics.java:223) ~[?:?]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:76) ~[spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0]



[12:40:20] [Craft Scheduler Thread - 112/WARN]: [Slimefun] Plugin Slimefun vv4.1.15 generated an exception while executing task 172
java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
        at org.mcstats.Metrics.postPlugin(Metrics.java:335) ~[?:?]
        at org.mcstats.Metrics.access$400(Metrics.java:57) ~[?:?]
        at org.mcstats.Metrics$1.run(Metrics.java:223) ~[?:?]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:76) ~[spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0]



[12:40:20] [Craft Scheduler Thread - 115/WARN]: [SlimeXpansion] Plugin SlimeXpansion v1.1.9 generated an exception while executing task 205
java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
        at org.mcstats.Metrics.postPlugin(Metrics.java:335) ~[?:?]
        at org.mcstats.Metrics.access$400(Metrics.java:57) ~[?:?]
        at org.mcstats.Metrics$1.run(Metrics.java:223) ~[?:?]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:76) ~[spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0]

获取在线玩家的事件？ 插件版本过老？不支持你的版本？

不清楚 我的核心是1.12.2 spigot，理论上是支持的

插件发布帖说支持吗

另外也许是你下载的 spigot 有损坏

是支持1.12.2的
以前也没报错

spigot是从官方下来的