Main class Code: package ewoplugPackage; import org.bukkit.Bukkit; import org.bukkit.plugin.java.JavaPlugin; public class Main extends JavaPlugin { public void onEnable() { Bukkit.getLogger().info("Hello. My names REEEEEMBOO"); } public void onDisable() { Bukkit.getLogger().info("Im bye back"); } } File plugin.yml Code: name: EwoPlug main: ewoplugPackage.Main version: 1.0.0 authors: [TaiDulloLa] Error Code: [09:23:28] [Server thread/WARN]: Legacy plugin EwoPlug v1.0.0 does not specify an api-version. [09:23:28] [Server thread/ERROR]: Could not load 'plugins\PluginsMe2.0.jar' in folder 'plugins' org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: ewoplugPackage/Main has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 60.0 at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:149) ~[spigot-1.17.1(1).jar:3284a-Spigot-3892929-0ab8487] at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:394) ~[spigot-1.17.1(1).jar:3284a-Spigot-3892929-0ab8487] at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:301) ~[spigot-1.17.1(1).jar:3284a-Spigot-3892929-0ab8487] at org.bukkit.craftbukkit.v1_17_R1.CraftServer.loadPlugins(CraftServer.java:409) ~[spigot-1.17.1(1).jar:3284a-Spigot-3892929-0ab8487] at net.minecraft.server.dedicated.DedicatedServer.init(DedicatedServer.java:233) ~[spigot-1.17.1(1).jar:3284a-Spigot-3892929-0ab8487] at net.minecraft.server.MinecraftServer.x(MinecraftServer.java:1010) ~[spigot-1.17.1(1).jar:3284a-Spigot-3892929-0ab8487] at net.minecraft.server.MinecraftServer.lambda$0(MinecraftServer.java:305) ~[spigot-1.17.1(1).jar:3284a-Spigot-3892929-0ab8487] at java.lang.Thread.run(Thread.java:831) [?:?] Caused by: java.lang.UnsupportedClassVersionError: ewoplugPackage/Main has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 60.0