Basically exactly what is described here in the archived forum in this post from 2018!
https://developer.xero.com/community-forum-archive/discussion/70563025
It's been 6 years. Is there really still no way to edit an invoice with a $0 balance? What are some best practices to avoid this? Just create a new invoice?
An issue we are encountering - we are unable to edit Authorised Invoices that have a Total of 0, on Xero it is marked as Paid (even though no payments are applied against it) so when we want to edit the invoice we are getting back the error
"Invoice not of valid status for modification"
HOWEVER, it is possible to just log on to the Xero website, edit the Invoice line-item amount to anything, and then we are able to edit the same invoice just fine over the API.
Since we are Partner application, you can't anticipate these use cases - when we push from our side, if it is making a new invoice that doesn't exist on Xero and the Total equals 0 we always send it as a DRAFT, but if it already exists on Xero as an AUTHORISED Invoice - we have no control over that.
Essentially what I am asking is, can it be fixed so that $0 AUTHORISED Invoices can be edited via API, since if it's a $0.1 AUTHORISED Invoice - we can edit it just fine.