Read the official Contao announcements.
Contao 2.10.0 is available
by Leo Feyer
Contao version 2.10.0 is available. The release includes all new features that have been presented at the Contao conference such as HTML5 and CSS3 support, global style sheet variables, compressed CSS and JS files and much more. In addition, over 220 tickets have been incorporated into the new version.
The Live Update from version 2.9.5 to 2.10.0 includes almost 1,500 files, if you upgrade from a prior version, it might be even more. This makes this update the biggest in the history of Contao which requires corresponding script timeout and memory limit settings. Therefore, check your server limits and php.ini settings before you start the Live Update.
In case the Live Update terminates prematurely, open the Contao installation directory (e.g. with your FTP client), find the system/constants.php file and reset VERSION and BUILD to the prior installed version (e.g. version 2.9 and build 5 for Contao 2.9.5). Then restart the Live Update.
Not all extensions in the Extension Repository are already available for version 2.10. Therefore, check your installed extensions before the update and update them accordingly or temporarily deactivate them in the back end settings.
If you need to use an extension which has not yet been approved for version 2.10, try to deactivate the request tokens in the back end settings. Most extensions should then run under Contao 2.10. Note, however, that this change decreases the security of your installation!
Information for web designers
In Contao 2.10, the tempate system has been reworked. Files with the extension .tpl have been replaced with .html5 files for generating HTML5 code and .xhtml files for generating XHTML code. Depending on the output format you want to use, it will suffice to rename existing .tpl files accordingly.
Also, the main page template, fe_page, has been modified. If you are using custom page templates, make sure to adjust them accordingly.
Information for developers
You will find all developer information in the announcement of Contao 2.10.RC1.
Find out what has been done
Download the release from github.com.