title: PHP: illegal session id
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1463175/session-hijacking-or-attack">Session hijacking or attack?</a>  </p>
  </blockquote>
  
  
  
  <p>Lately I am receiving following error on my site</p>
  
  <pre><code>PHP Warning:  session_start(): The session id is too long or contains illegal characters, valid characters are a-z, A-Z, 0-9 and '-,'
  </code></pre>
  
  <p>This error occurs on this line <code>session_start()</code> does anybody have idea why its happening?</p>
  
  <p>Thanks</p>