"headers already sent" error after file upload
<p>After I uploaded my files this kind of error is occurred. But there is no any errors in my localhost. What kind of error is this? How to fix this?</p>

<blockquote>
  <p>Warning: session_start() [function.session-start]: Cannot send session
  cookie - headers already sent by (output started at
  /home/lahiruca/public_html/events/includes/links.php:1) in
  /home/lahiruca/public_html/events/includes/header.php on line 1</p>
</blockquote>

<p>(from the comments)</p>

<pre><code>&lt;?php session_start();?&gt; 
&lt;div class="header"&gt; 
&lt;div class="logo"&gt;&lt;/div&gt; 
&lt;div class="right_header"&gt; 
&lt;div class="top_right_header"&gt; 
  &lt;ul&gt; &lt;?php if(isset($_SESSION['userid'])){ ?&gt; 
</code></pre>
