Hi! The invoice number system is quite robust, and all ocurrences of ‘missing’ invoice numbers in the past (at least since 2.0 which included major improvements) have been caused by other factors, here’s a list of some of them:
- Doing bulk exports and including older orders that didn’t have an invoice before (i.e. not visible in your order list but possibly assigned to orders on later pages) – the invoice numbers are tied to the moment of creation of the invoice, not that of the order
- Test orders that were deleted by an admin but no reset of the ‘next invoice number’ setting
- My account option for allowing invoice download set to an option other than “Only when an invoice has already been created/emails”, which would make it possible for customers to create invoices for older orders even when they didn’t have an invoice/invoice number yet
- If you are using our Professional extension and have set the Proforma or Credit Note invoice numbers to use the main invoice numbering sequence
- If you are using PayPal and have set up both IPN and PDT for confirming order payments (this would typically cause all invoices for PayPal payments to have one number skipped though, which doesn’t seem to be the case here, more information here)
Let us know if you think any of the above could apply here! You may want enter the missing invoice number in the search box just to see if that turns up something.
