I updated my site yesterday to PHP 5.4.41 Now whenever anyone logs in anywhere on the site I get a blank page. Clicking the back button brings you back to the page shows you as logged in. What has changed?
What aMember version do you have installed? Try to add this to the top of /amember/application/configs/config.php file : PHP: <?php define('AM_DEBUG', true); ?> then try to login again. That will enable debug output so you should see an error instead of blank page.