I recently upgraded to JFBC 4.2.1 and my login in page quit working (blank page). After disabling nearly everything in an effort to resolve the issue I finally determined that Gantry-based templates were the cause. I have three installed on my site and tried all of them. Other templates work. Everything worked fine with 4.1.2, including templates using Gantry.
Accessing the login page with 4.2.1 produces the following in the PHP error log:
PHP Notice: Undefined variable: gantry in /Applications/MAMP/htdocs/itasteit16/templates/rt_ionosphere/html/com_users/login/default_login.php on line 14
PHP Fatal error: Call to a member function init() on a non-object in /Applications/MAMP/htdocs/itasteit16/templates/rt_ionosphere/html/com_users/login/default_login.php on line 14
Here are the first few lines of code for the above-referenced default_login.php:
defined('_JEXEC') or die;
JHtml::_('behavior.keepalive');
require_once(JPATH_LIBRARIES.'/gantry/gantry.php');
$gantry->init();
gantry_import('core.utilities.gantryjformfieldaccessor');
Ok, so $gantry doesn't exist when this file is loaded, causing the fatal PHP error. Something changed from 4.1.2 to 4.2.1.
NOTE: The SCLogin module works, as does the default Joomla Login module. The issue (blank page) is caused when trying to access the Login form through the menu. Also curious is the fact that, once logged in, I can access the form (no blank page).
Thanks!