I need help... ive been trying to solve this for a time now and... yeah well...

This happen on the server console:
[00:04:15 INFO]: Pyrocringe issued server command: /shopkeepers
[00:04:15 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'shopkeepers' in plugin Shopkeepers v1.86
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:181) ~[craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at org.bukkit.craftbukkit.v1_8_R1.CraftServer.dispatchCommand(CraftServer.java:643) ~[craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at net.minecraft.server.v1_8_R1.PlayerConnection.handleCommand(PlayerConnection.java:1083) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at net.minecraft.server.v1_8_R1.PlayerConnection.a(PlayerConnection.java:918) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at net.minecraft.server.v1_8_R1.PacketPlayInChat.a(PacketPlayInChat.java:26) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at net.minecraft.server.v1_8_R1.PacketPlayInChat.a(PacketPlayInChat.java:53) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at net.minecraft.server.v1_8_R1.PacketHandleTask.run(SourceFile:13) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_101]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_101]
at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:686) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:627) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:530) [craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_101]
Caused by: java.lang.NoSuchMethodError: org.bukkit.entity.Player.getTargetBlock(Ljava/util/Set;I)Lorg/bukkit/block/Block;
at com.nisovin.shopkeepers.CommandManager.onCommand(CommandManager.java:469) ~[?:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[craftbukkit.jar:git-Spigot-da32fe1-df0b4c1]
... 14 more

and this happens in game:
An internal error occured while attempting to perform this command

The Shopkeeper plugin version you are using is incompatible with the specific spigot server version you are using. Either downgrade shopkeepers, or upgrade your spigot server (recommended).