Warning! Before you upgrade, if you use the raw PHP-style URL scheme...

If you upgrade to this release and are using the raw PHP-style URL scheme (default), the single public zone option will be forced on for your site to work around a bug which could lock members out of your site.

Please see tracker issue #6166 for more information.

If you want to work around this (you need the 'site' zone to be separate), before upgrading, change your URL scheme to a different option other than raw URLs. The "Use /pg/ to identify CMS pages" setting will work best without further configuration necessary on your part. Make sure your web server supports URL rewrites, and you have an .htaccess file present (copy recommended.htaccess if not).

Other important upgrade information

• Composr now requires the PHP gettext extension so location-based functionality works.
• Telemetry has changed. Review and change your settings under Admin Zone > Setup > Configuration > Privacy / legal compliance options after upgrading.
• Parental consent ("COPPA") settings have changed. See Admin Zone > Setup > Edit parental control settings (and the indicated tutorial) after upgrading. You and your members may be prompted to enter your Date of Birth, Time zone, and Region after upgrade (due to the default configuration).
• The multi_lang_content option in _config.php is now ignored; the value is migrated into the database and will be interpreted from there on. This was never meant to be hand-edited by the webmaster. Instead, to enable or disable content translations, use data_custom/execute_temp.php to run require_code('database_multi_lang_conv'); enable_content_translation(); to enable, or require_code('database_multi_lang_conv'); disable_content_translation(); to disable. Back up your database, and close your site, before you do either! And make sure you have a large execution time limit on PHP and your webserver / upstream proxies.
• These non-bundled addons have been removed / archived: performance_compile (obsolete), simplified_emails (obsolete), confluence (self-hosted instance not supported), SugarCRM (community edition deprecated), Bantr (very niche), world_regions (obsolete), and locations_catalogues (broken, but hopefully will be fixed / brought back later). See 0005687: Addons to archive / remove from the codebase (ongoing) - Composr CMS feature tracker.
• These new bundled addons will be installed upon upgrade automatically: core_locations (geolocation code refactored to this addon, and PHP ISO Codes library added)