Trying to create a speed plugin for 1.2.5: Code: package org.mcmegacraft.Speedifier; import org.bukkit.ChatColor; import org.bukkit.command.Command; import org.bukkit.command.CommandSender; import org.bukkit.entity.Player; import org.bukkit.plugin.java.JavaPlugin; public class Speedifier extends JavaPlugin { @Override public void onEnable() { getLogger().info("Speedifier v0.1 enabled!"); } @Override public void onDisable() { getLogger().info("Speedifier v0.1 disabled!"); } @Override public boolean onCommand(CommandSender sender, Command command, String label, String[] args) { if (command.getName().equalsIgnoreCase("speed")) { if (!(sender instanceof Player)) { sender.sendMessage(ChatColor.RED + "Only players can use this command."); return true; } Player player = (Player) sender; if (args.length != 1) { player.sendMessage(ChatColor.YELLOW + "Usage: /speed <value>"); return true; } try { float speed = Float.parseFloat(args[0]); if (speed < 0 || speed > 1) { player.sendMessage(ChatColor.RED + "Speed must be between 0 and 1."); return true; } // Set both walk speed and fly speed player.setWalkSpeed(speed); // Default walk speed is 0.2 player.setFlySpeed(speed); // Default fly speed is 0.1 player.sendMessage(ChatColor.GREEN + "Speed has been set to " + speed); } catch (NumberFormatException e) { player.sendMessage(ChatColor.RED + "Invalid speed value. Please enter a number."); } return true; } return false; } } The method setWalkSpeed(float) is undefined for the type Player The method setWalkSpeed(float) is undefined for the type Player