 <p>PHP cannot find the index referer in the variable $_GET, you should first test if the index exist, Try this:</p> <p><strong>PHP</strong></p> <pre><code>&lt;input id="refer" placeholder="&lt;?php echo $txt['not_oblige']; ?&gt;" type="text" name="referer" value="&lt;?php echo (isset($_GET['referer'])) ? $_GET['referer'] : '' ; ?&gt;" class="form-control" /&gt; </code></pre>