Access denied. You are not authorized to access this page. Log in using either an account with the administer software updates permission or the site maintenance account (the account you created during installation). If you cannot log in, you will have to edit settings.php to bypass this access check. To do this:

    With a text editor find the settings.php file on your system. From the main Drupal directory that you installed all the files into, go to sites/your_site_name if such directory exists, or else to sites/default which applies otherwise.
    There is a line inside your settings.php file that says $update_free_access = FALSE;. Change it to $update_free_access = TRUE;.
    As soon as the update.php script is done, you must change the settings.php file back to its original form with $update_free_access = FALSE;.
    To avoid having this problem in the future, remember to log in to your website using either an account with the administer software updates permission or the site maintenance account (the account you created during installation) before you backup your database at the beginning of the update process.