diff --git a/helper/json.format.php b/helper/json.format.php
index 230cdfa..fb8d35b 100644
--- a/helper/json.format.php
+++ b/helper/json.format.php
@@ -1,11 +1,12 @@
 <?php
-// @date 2019-10-13
+// @created_on 2019-10-13
+// @updated_on 2020-01-27
 // @author Go Namhyeon <gnh1201@gmail.com>
 
 if(!check_function_exists("json_decode_ex")) {
     function json_decode_ex($data, $options=array()) {
         $result = false;
-        
+
         $is_assoc = array_key_equals("assoc", $options, true);
 
         $invalid_fn = array(
@@ -13,13 +14,15 @@ if(!check_function_exists("json_decode_ex")) {
             "NO_FUNCTION_JSON_LAST_ERROR" => "json_last_error",
         );
         $error = check_invalid_function($invalid_fn);
-
-        if($error < 0) {
+        if($error == JSON_ERROR_NONE) {
             if($is_assoc) {
                 $result = json_decode($data, true);
             } else {
                 $result = json_decode($data);
             }
+        } else {
+            $result = new stdClass();
+            $result->error = $error;
         }
 
         return $result;
@@ -31,20 +34,34 @@ if(!check_function_exists("json_encode_ex")) {
         $result = false;
         
         $is_adaptive = array_key_equals("adaptive", $options, true);
-
-        if($is_adaptive) {
-            // 2018-06-01: Adaptive JSON is always quotes without escape non-ascii characters
-            $lines = array();
-            foreach($data as $k=>$v) {
-                if(is_array($v)) {
-                    $lines[] = sprintf("\"%s\":%s", make_safe_argument($k), get_adaptive_json($v));
+        $is_pretty = array_key_equals("pretty", $options, true);
+        
+        $invalid_fn = array(
+            "NO_FUNCTION_JSON_ENCODE" => "json_decode",
+            "NO_FUNCTION_JSON_LAST_ERROR" => "json_last_error",
+        );
+        $error = check_invalid_function($invalid_fn);
+        if($error == JSON_ERROR_NONE) {
+            if($is_adaptive) {
+                // 2018-06-01: Adaptive JSON is always quotes without escape non-ascii characters
+                $lines = array();
+                foreach($data as $k=>$v) {
+                    if(is_array($v)) {
+                        $lines[] = sprintf("\"%s\":%s", make_safe_argument($k), get_adaptive_json($v));
+                    } else {
+                        $lines[] = sprintf("\"%s\":\"%s\"", make_safe_argument($k), make_safe_argument($v));
+                    }
+                }
+                $result = "{" . implode(",", $lines) . "}";
+            } else {
+                if($is_pretty) {
+                    $result = json_encode($data, JSON_PRETTY_PRINT);
                 } else {
-                    $lines[] = sprintf("\"%s\":\"%s\"", make_safe_argument($k), make_safe_argument($v));
+                    $result = json_encode($data);
                 }
             }
-            $result = "{" . implode(",", $lines) . "}";
         } else {
-            $result = json_encode($data);
+            $result = sprintf("{\"error\": \"%s\"}", $error);
         }
 
         return $result;