If your attendees are not able to register for an event because it is not on sale or is sold out, you can adjust some settings on the Admin side to allow registrations again.
Event Not On Sale
Your event will appear as Not On Sale if event registration is closed or the public settings for all attendees is set to No.
The first thing to do is check your event Settings to see if the registration is closed. If the Registration dropdown shows as Closed, a person cannot register for the event. If you want attendees to be able to sign up for the event, change this to Open.
If registration is open, but your event is still showing as Not On Sale, make sure that at least one of your attendee types is set to public. If the Public setting is No for all attendees, your event will show as Not On Sale on the public page.
Event Sold Out or Full
If the total capacity of an event or the maximum number of a specific attendee type has been reached, the event will appear as Sold Out. To allow additional registrations, update the event or attendee type capacities.
If the total capacity of an event has been reached, the whole event will appear as Sold Out.
An attendee type will appear as Sold Out if the capacity for that attendee type has been reached. An attendee type will appear as Full if the capacity for that event has been reached and the registration fee for the attendee type is $0.
You can check the maximum number of attendees for the whole event as well as the maximum number for each attendee type in Settings. The Event Capacity is the maximum number of attendees for the event. The maximum number of attendees for each attendee type is listed under the Event Capacity.
Attendee Type Doesn't Show
If an attendee type does not appear on the event registration page, check the Attendee Type settings. If the Public setting is No, the attendee type can only be accessed from the Admin side; it will not appear on the public registration page.