Unsupported Version.

I am using (Bukkit-1.7.9-RO.2). My server is spigot 1.8.1 and this error appears.

Code:

31.01 00:03:37 [Server] INFO ... 20 more
31.01 00:03:37 [Server] INFO at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at java.lang.Class.forName(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.lang.Class.forName0(Native Method) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.security.AccessController.doPrivileged(Native Method) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.net.URLClassLoader$1.run(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.net.URLClassLoader$1.run(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.net.URLClassLoader.access$100(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.net.URLClassLoader.defineClass(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.security.SecureClassLoader.defineClass(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.lang.ClassLoader.defineClass(Unknown Source) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.7.0_72]
31.01 00:03:37 [Server] INFO Caused by: java.lang.UnsupportedClassVersionError: me/kowagatte/effectdrop/effectDrop : Unsupported major.minor version 52.0
31.01 00:03:37 [Server] INFO at java.lang.Thread.run(Unknown Source) [?:1.7.0_72]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:526) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:623) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:683) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.7.0_72]
31.01 00:03:37 [Server] INFO at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.7.0_72]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.PacketHandleTask.run(SourceFile:13) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.PacketPlayInChat.a(PacketPlayInChat.java:53) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.PacketPlayInChat.a(PacketPlayInChat.java:26) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.PlayerConnection.a(PlayerConnection.java:950) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at net.minecraft.server.v1_8_R1.PlayerConnection.handleCommand(PlayerConnection.java:1115) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.craftbukkit.v1_8_R1.CraftServer.dispatchCommand(CraftServer.java:646) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:25) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.Bukkit.reload(Bukkit.java:534) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.craftbukkit.v1_8_R1.CraftServer.reload(CraftServer.java:744) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.craftbukkit.v1_8_R1.CraftServer.loadPlugins(CraftServer.java:291) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:135) ~[Spigot18.jar:git-Spigot-d0d1d87-bc03b6f]
31.01 00:03:37 [Server] INFO org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: me/kowagatte/effectdrop/effectDrop : Unsupported major.minor version 52.0
31.01 00:03:37 [Server] ERROR Could not load 'plugins/effectDrop.jar' in folder 'plugins'

I have tried, craftbukkit 1.7.9-RO.2, craftbukkit 1.7.10, and other versions but I get a similar error.

 

@87pen You're using Java 7 to run your server? That plugin was compiled in Java 8.

 

Moved to Alternatives Section.