title: Update Joomla from 2.5.28 to 3.4.0
body: <p>I need to update my joomla website which current version is 2.5.28. Now I'm trying to update it using this:</p>
  
  <ul>
  <li>I use XAMPP as a server environment (PHP 5.4, MySQL 5.6)</li>
  <li>Use a backup of my site</li>
  <li>Also use astable version of joomla 2.5.28</li>
  </ul>
  
  <p>I tried to update with both sites, the stable one and my one, but every time I get errors.</p>
  
  <p>If I want to update my site I do this:</p>
  
  <ul>
  <li>check for updates and update all things <strong>but for</strong> the JSN air template</li>
  <li>go to joomla update, click on options on the right side and choose short time support, save and close</li>
  <li>click update button</li>
  </ul>
  
  <p>With the stable site I nearly do the same:</p>
  
  <ul>
  <li>go to joomla update, click on options on the right side and choose short time support, save and close</li>
  <li>click update button</li>
  </ul>
  
  <p>I said above that I get errors. If I want to update the stable one I get these results/errors:</p>
  
  <ul>
  <li>after updating it completely (100%) I get a white page with an url like <strong>"<a href="http://localhost/stable/administrator/index.php?option=com_joomlaupdate&amp;task=update.finalise" rel="nofollow">http://localhost/stable/administrator/index.php?option=com_joomlaupdate&amp;task=update.finalise</a>"</strong></li>
  <li>if I reload the page after getting the white page I get an error like <strong>"Can't DROP 'usertype'; check that column/key exists SQL=ALTER TABLE <code>bcyqr_users</code> DROP KEY <code>usertype</code>;"</strong></li>
  <li>if I reload the page again I get an error like "Table 'stable.bcyqr_postinstall_messages' doesn't exist SQL=SHOW FULL COLUMNS FROM <code>bcyqr_postinstall_messages</code>"</li>
  </ul>
  
  <p>I looked in the database and I have a column with name "usertype". What happened? Why it can't be deleted?</p>
  
  <p>I think it's strange that it doesn't function with the normal joomla settings. On youtube I saw videos in which the people just did the steps I also did. </p>
  
  <p>And with my site I get the following errors:</p>
  
  <ul>
  <li>18 times: Use of undefined constant DS - assumed 'DS' in C:\xampp\htdocs\mysite\administrator\components\com_poweradmin\defines.poweradmin.php </li>
  <li>1 time: Class 'JSNConfigHelper' not found in C:\xampp\htdocs\mysite\plugins\system\jsnpoweradmin\jsnpoweradmin.php</li>
  </ul>
  
  <p>I googled that error, so I used this extension: 
  <a href="http://digitaldisseny.com/en/joomla-extensions/solve-undefined-ds-constant-joomla-3-error" rel="nofollow">http://digitaldisseny.com/en/joomla-extensions/solve-undefined-ds-constant-joomla-3-error</a></p>
  
  <p>But then I couldn't update the joomla. I get a popup dialog with message <strong>"Invalid login"</strong>.</p>
  
  <p>I don't know what to do to update the joomla. Can you help me? What I do wrong?</p>
  
  <p>Thanks.</p>