You can't uncancel or reinstate a session.

However, you can quickly and easily create a new session using a cancelled or live class as a template. To do this, simply go to Schedule > Add new session > Copy an existing session > select Show all on the calendar pop-up > select your recently cancelled session.

If you would like to add the previous attendees on this cancelled session to this newly created one, you can easily do this by going to the Attendees tab on this new session > Add attendee.

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How do I update or cancel a class / session?

Schedule