Xero Sync Error - Invoice number must be unique

Problem Statement

Sync to Xero fails with "Invoice number must be unique." This occurs when Xero already has an invoice with the same invoice number.

Solution

The error means there is already an invoice in Xero with that number. Chargebee cannot fix this automatically because it cannot determine whether the duplicate was created manually in Xero or is due to overlapping numbering in Chargebee and Xero.

What you can do:

• If the invoice was created manually in Xero with the same number, Chargebee can mark that invoice as ignored for future syncs so the error does not repeat.
• If numbering in Chargebee and Xero is causing conflicts, adjust the invoice number prefix in either Chargebee or Xero so they no longer overlap. You may need to add the correct invoice manually in Xero once; Chargebee can then set the sync to ignore this specific error for that invoice.

Resolve the duplicate or numbering on your side, then re-run sync or use the ignore option as appropriate.