You have to upgrade your core Moodle version AND the Configurable Reports plugin. You can't run the latest version of Configurable Reports on Moodle 2.8.
And you can't upgrade Configurable Reports without upgrading Moodle.
Best to review the Moodle Upgrade documentation at https://docs.moodle.org/311/en/Upgrading.
And you can't upgrade Configurable Reports without upgrading Moodle.
Best to review the Moodle Upgrade documentation at https://docs.moodle.org/311/en/Upgrading.