For some reason, several of my users have been trying to directly embed Base-64 encoded images into their posts. The XF image proxy attempts to process them, but it fails, breaking many other resources on the thread page including smilies, avatars, even stylesheets (they show an ERR_CONNECTION_RESET in the Chrome dev console). When I've tried this in the test forum here, the image proxy appears to fail gracefully and display the software's regular broken image placeholder. Why does my site behave differently? I'm using XF 1.5.6, PHP-FPM 5.6.18, Nginx 1.9.11, with PHP GD set as the default image processor.