session_start（）：无法发送会话cookie-已发送的标头。在postign请求中在codeigniter rest-server api liberay中

Question

我正在使用rest-server库为API使用codeigniter框架。 我已经在本地主机上使用邮递员进行了测试，但登录时未显示错误，但是当我在名称服务器上上传代码时。现在，我在请求后收到此错误。我不明白为什么会发生此错误。

<div style="border:1px solid #990000;padding-left:20px;margin:0 0 10px 0;">
    <h4>A PHP Error was encountered</h4>
    <p>Severity: Warning</p>
    <p>Message:  session_start(): Cannot send session cookie - headers already sent by (output started at /public_html/application`enter code here`/controllers/api/Users.php:192)</p>
    <p>Filename: Session/Session.php</p>
    <p>Line Number: 143</p>
    <p>Backtrace:</p>
    <p style="margin-left:10px">
            File: public_html/application/libraries/REST_Controller.php
        <br />
            Line: 397
        <br />
            Function: __construct
    </p>
    <p style="margin-left:10px">
    /public_html/application/controllers/api/Users.php
        <br />
            Line: 14
        <br />
            Function: __construct
    </p>
    <p style="margin-left:10px">
            File: /public_html/index.php
        <br />
            Line: 315
        <br />
            Function: require_once
    </p>
</div>
<div style="border:1px solid #990000;padding-left:20px;margin:0 0 10px 0;">
    <h4>A PHP Error was encountered</h4>
    <p>Severity: Warning</p>
    <p>Message:  session_start(): Cannot send session cache limiter - headers already sent (output started at /public_html/application/controllers/api/Users.php:192)</p>
    <p>Filename: Session/Session.php</p>
    <p>Line Number: 143</p>
    <p>Backtrace:</p>
    <p style="margin-left:10px">
            File: /public_html/application/libraries/REST_Controller.php
        <br />
            Line: 397
        <br />
            Function: __construct
    </p>
    <p style="margin-left:10px">
            File: /public_html/application/controllers/api/Users.php
        <br />
            Line: 14
        <br />
            Function: __construct
    </p>
    <p style="margin-left:10px">
            File: /public_html/index.php
        <br />
            Line: 315
        <br />
            Function: require_once
    </p>
</div>