diff --git a/src/main/java/com/github/jie65535/opencommand/OpenCommandHandler.java b/src/main/java/com/github/jie65535/opencommand/OpenCommandHandler.java
index c06d007..71c6dd3 100644
--- a/src/main/java/com/github/jie65535/opencommand/OpenCommandHandler.java
+++ b/src/main/java/com/github/jie65535/opencommand/OpenCommandHandler.java
@@ -46,6 +46,8 @@ public void applyRoutes(Javalin javalin) {
     private static final Map<String, Integer> codes = new HashMap<>();
     private static final Int2ObjectMap<Date> codeExpireTime = new Int2ObjectOpenHashMap<>();
 
+    private static final Int2ObjectMap<MessageHandler> playerMessageHandlers = new Int2ObjectOpenHashMap<>();
+
     public static void handle(Context context) {
         var plugin = OpenCommandPlugin.getInstance();
         var config = plugin.getConfig();
@@ -152,13 +154,18 @@ public static void handle(Context context) {
                     return;
                 }
                 // Player MessageHandler do not support concurrency
+                var handler = playerMessageHandlers.get(player.getUid());
+                if (handler == null) {
+                    handler = new MessageHandler();
+                    playerMessageHandlers.put(player.getUid(), handler);
+                }
                 //noinspection SynchronizationOnLocalVariableOrMethodParameter
-                synchronized (player) {
+                synchronized (handler) {
                     try {
-                        var resultCollector = new MessageHandler();
-                        player.setMessageHandler(resultCollector);
+                        handler.setMessage("");
+                        player.setMessageHandler(handler);
                         CommandMap.getInstance().invoke(player, player, command);
-                        context.json(new JsonResponse(resultCollector.getMessage()));
+                        context.json(new JsonResponse(handler.getMessage()));
                     } catch (Exception e) {
                         plugin.getLogger().warn("Run command failed.", e);
                         context.json(new JsonResponse(500, "error", e.getLocalizedMessage()));
diff --git a/src/main/java/com/github/jie65535/opencommand/OpenCommandPlugin.java b/src/main/java/com/github/jie65535/opencommand/OpenCommandPlugin.java
index 1e2aadd..7b9649b 100644
--- a/src/main/java/com/github/jie65535/opencommand/OpenCommandPlugin.java
+++ b/src/main/java/com/github/jie65535/opencommand/OpenCommandPlugin.java
@@ -29,6 +29,8 @@
 import emu.grasscutter.utils.JsonUtils;
 
 import java.io.*;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 
 public final class OpenCommandPlugin extends Plugin {
 
@@ -105,8 +107,9 @@ private void loadConfig() {
                 getLogger().error("[OpenCommand] Unable to save config file.");
             }
         } else {
-            try (var fileReader = new InputStreamReader(new FileInputStream(configFile))) {
-                config = JsonUtils.loadToClass(fileReader, OpenCommandConfig.class);
+            try {
+                config = JsonUtils.decode(Files.readString(configFile.toPath(), StandardCharsets.UTF_8),
+                        OpenCommandConfig.class);
             } catch (Exception exception) {
                 config = new OpenCommandConfig();
                 getLogger().error("[OpenCommand] There was an error while trying to load the configuration from config.json. Please make sure that there are no syntax errors. If you want to start with a default configuration, delete your existing config.json.");
@@ -125,8 +128,9 @@ private void loadData() {
             data = new OpenCommandData();
             saveData();
         } else {
-            try (var fileReader = new InputStreamReader(new FileInputStream(dataFile))) {
-                data = JsonUtils.loadToClass(fileReader, OpenCommandData.class);
+            try {
+                data = JsonUtils.decode(Files.readString(dataFile.toPath(), StandardCharsets.UTF_8),
+                        OpenCommandData.class);
             } catch (Exception exception) {
                 data = new OpenCommandData();
                 getLogger().error("[OpenCommand] There was an error while trying to load the data from data.json. Please make sure that there are no syntax errors. If you want to start with a default data, delete your existing data.json.");