Counter not resetting after Canceled Order

Hello Mitko,
What you describe (reusing invoice numbers) would cause legal issues in many countries – once an invoice has been issues you should not delete it. Additionally, setting the counter back by 1 only works if there has not been another new order in the mean time. Instead, you could make sure the invoice is not created until the order is final (for example when it has the “Processing” order status), via the attachment settings. That way you won’t get invoice numbers for orders that are never paid and then canceled.
Orders that have been paid and are refunded can be handled with a credit note – this is a negative invoice to make the balance zero. Credit notes can be created with WooCommerce PDF Invoices & Packing Slips Professional, and they can either user the main invoice number sequence (e.g. invoice 101, credit note 102, invoice 103, etc.) or use a separate credit note number sequence (e.g. invoice 101, credit note 101, invoice 102, etc.). If you have any further questions about that, don’t hesitate to contact us via email at [email protected] (this forum is only meant for the free plugin).

Thank you! That should resolve the issue.

Regards,
Mitko