After successfully using square invoicing for several months, and successfully sending 8 invoices today, now I cannot send any additional invoices to customers. I keep getting an 'id was already used, please use a new id' error message?
It sounds like you have an invoice with a duplicate ID number. In the top right corner under Details, the second bar is the invoice ID.You should be able to choose the next number in the sequence and send your invoice.
This can happen if you have an invoice saved as a draft with the same number. If you have any other invoice questions please let me know! 🙂