This article will explain the differences between "Voiding" and "Cancelling" an Invoice and how to properly use each function.
The Return/Cancel button on an invoice should be used if a transaction actually occurred, but the customer changed their mind. This process will leave a history of the purchase on the customer's record.
The Void button on an invoice should be used when you make a mistake. It removes the history of the purchase from the customer's record. If the original transaction batch is open, netFORUM literally erases the transaction from the batch. If the original transaction batch is closed, you must select a new batch and void with adjustment; this will create reversing transactions in the new batch.
You should not use Void or Return/Cancel on invoices for Event or Exhibitor Registrations. Currently, Void functionality is not available for these invoices
For an event registrant, use the Cancel Registrant process.