Upgrading to Moodle 1.8
From MoodleDocs
Moodle1.8
If you are upgrading to 1.8 from something earlier than 1.6, then read Upgrading to Moodle 1.6.
If you are upgrading from 1.6, please note that a major new feature in Moodle 1.7 onwards - Roles and capabilities.
More to come here soon...