Here are the steps you need to take in the unfortunate event that you need to cancel an event.
1) Notify ticket buyers
Send an email to all ticket buyers using the Broadcast feature. Explain that the event has been cancelled, and, if applicable when they should expect their refund or voucher to be issued. You may want to think about what other questions people may have and answer this in the email too, to prevent your ticket buyers from responding with more questions.
2) Update your event status
Set your event status to 'Sales closed':
A popup will appear as shown below. Select the option 'Set custom status' and write 'Cancelled' in the text box as shown below. Add any useful information for customers, as this will appear on the event page.
3) Process refunds as soon as possible (if applicable)
It's advisable to process refunds as soon as possible. If refunds are delayed, or ticket buyers are confused about whether they are entitled to a refund, it can lead to your customers processing a dispute with their bank which can lead to a huge administrative burden for you, and if you lose the dispute, having to pay dispute fees on top of the refund. Learn more about disputes.
If you want to issue a voucher for a future event, instead of a refund, you can do so via your orders dashboard.
If you are using Paypal or Stripe, you can cancel and refund your customer from your orders dashboard.
If you are using offline payment methods, you will need to process your refunds via the payment method you used to collect your payment.