Read the official Contao announcements.
Contao 3.1.1 is available
by Leo Feyer – Announcements
Contao version 3.1.1 is available. The bugfix release fixes several plugin issues, including the missing slider support in IE8, the wrong generation of the CSS3PIE file path and the wrong assignment of the dollar function to jQuery instead of MooTools.
In addition, the subscribable newsletter channels when editing users (back end) and members (front end) are now displayed correctly again.