php返回數(shù)組給ajax出錯

我通過php生成了一個數(shù)組，并echo回去，ajax進(jìn)入error（ajax的datatype設(shè)為json），我推斷原因在于返回的不是json格式。

求大神幫看看，感謝！

ajax部分：

$("#ricotext").keyup(function(){
                $.ajax({
                  type:"post",
                  url:"search.php",
                  dataType:"json",
                  data:{search:$("#ricotext").val()},
                  success:function(feedbackdata)
                    {
                      console.log(feedbackdata);
                      console.log(success);
                    },
                  error:function(feedbackdata)
                    {
                      console.log(feedbackdata);
                      console.log(error);
                    },
                });
            });

php部分：

<?php
        $servername = "localhost";
        $username = "root";
        $password = "root";
        $dbname = "guitartabs";
        $search=$_POST["search"];
         
        $conn = new mysqli($servername, $username, $password, $dbname);
        // Check connection
        if ($conn->connect_error) {
            die("連接失敗: " . $conn->connect_error);
        } 
         
        $sql = "SELECT * FROM tabs where name like '%$search%' OR singer like '%$search%'";
        $result = $conn->query($sql);
         
        $num_results = $result->num_rows;

        if ($result->num_rows > 0) {
         //生成空數(shù)組
            $backresults=array();
            for($i=0;$i<$num_results;$i++){
                $row = $result->fetch_assoc();
         //遍歷選項并將信息寫入數(shù)組中
                array_push($backresults,array("name"=>$row['name'],"singer"=>$row['singer'],"address"=>$row['address']));
            };
         //返回給ajax該數(shù)組
             echo(json_encode($backresults));
        } else {
            echo "抱歉，本站暫時未收錄該樂譜。";
        }
        $conn->close();
    ?>

chrome瀏覽器收到的數(shù)據(jù)是：

[{"name":"NightWish","singer":"NightWish","address":"uploads\/NightWish.gp5"},{"name":"night","singer":"rico","address":"uploads\/MultiTrack.gp5"},{"name":"nightbar","singer":"ricoq","address":"uploads\/Serenade.gp5"}]

同時console.log打印

readyState: 4

error

說明進(jìn)入了error。
我覺得如果echo的是一個json對象應(yīng)該就能解決問題。
請教一下如何解決？