MCmmo error

So I want to use the plugin mcmmo for my server but whenever it tries to enable the plugin, the console gives me a bunch of errors and I would just like to know how to fix it so I can use the plugin so please help me !!!!

Console:

06.07 12:20:49 [Server] ERROR [mcMMO] There was an error while enabling mcMMO!
06.07 12:20:49 [Server] WARN java.lang.NoSuchMethodError: org.bukkit.configuration.file.YamlConfiguration.loadConfiguration(Ljava/io/InputStreamLorg/bukkit/configuration/file/YamlConfiguration;
06.07 12:20:49 [Server] WARN at com.gmail.nossr50.config.HiddenConfig.load(HiddenConfig.java:31) 06.07 12:20:49 [Server] WARN at com.gmail.nossr50.config.HiddenConfig.<init>(HiddenConfig.java:18) 06.07 12:20:49 [Server] WARN at com.gmail.nossr50.config.HiddenConfig.getInstance(HiddenConfig.java:23)
06.07 12:20:49 [Server] WARN at com.gmail.nossr50.mcMMO.loadConfigFiles(mcMMO.java:400)
06.07 12:20:49 [Server] WARN at com.gmail.nossr50.mcMMnEnable(mcMMO.java:134)
06.07 12:20:49 [Server] WARN at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:264)
06.07 12:20:49 [Server] WARN at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:329)
06.07 12:20:49 [Server] WARN at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:401)
06.07 12:20:49 [Server] WARN at org.bukkit.craftbukkit.v1_12_R1.CraftServer.enablePlugin(CraftServer.java:361)
06.07 12:20:49 [Server] WARN at org.bukkit.craftbukkit.v1_12_R1.CraftServer.enablePlugins(CraftServer.java:323)
06.07 12:20:49 [Server] WARN at org.bukkit.craftbukkit.v1_12_R1.CraftServer.<init>(CraftServer.java:261) 06.07 12:20:49 [Server] WARN at net.minecraft.server.v1_12_R1.PlayerList.<init>(PlayerList.java:74)
06.07 12:20:49 [Server] WARN at net.minecraft.server.v1_12_R1.DedicatedPlayerList.<init>(SourceFile:14) 06.07 12:20:49 [Server] WARN at net.minecraft.server.v1_12_R1.DedicatedServer.init(DedicatedServer.java:186)
06.07 12:20:49 [Server] WARN at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:521)
06.07 12:20:49 [Server] WARN at java.lang.Thread.run(Thread.java:745)
06.07 12:20:49 [Server] INFO [mcMMO] Disabling mcMMO v1.5.00-b3547
06.07 12:20:49 [Server] ERROR Error occurred while disabling mcMMO v1.5.00-b3547 (Is it up to date?)