We are going to make necessary and critical updates to our systems during this timeframe. While we anticipate using only a portion of the time, members should be prepared for the site being offline for the full 3 days. During this maintenance window www.cali.org and other sites including Classcaster, Lawbooks, and our authoring systems will be unavailable.
Looks like you followed a bad link that tried to open a CALI Lesson directly. That is not allowed. If you were trying to start a Lesson assigned by your professor you should contact them for a valid LessonLink to start the Lesson and report the grade back to them.