This article may be out of date!
Visit the New Knowledge Center

Xero Error Message: Invoice # must be unique


  • Xero Sync Failure shows "Invoice # must be unique". 


  • Clio Manage
  • Xero

Additional Information:

Most common reasons this occurs:

  1. An Invoice was voided and recreated before Xero was able to release the number. A simple edit on the Invoice (change anything and then change it back) in Clio will get Clio to try again on the next cycle.

  2. Interest accumulates on its own ‘hidden’ Bills in Clio and appear in Xero as their own Invoices. They use up Invoice #’s, and some customers notice ‘gaps’ in the visible numbers in Clio and make manual edits to ‘correct’ it.

  3. You may have been manually renumbering Invoices in Clio to follow an unsupported scheme. Commonly done to make Invoice Numbers per Client (ie/ Repeats 1, 2, 3, etc for each Client), resulting in duplicates.


This error usually occurs whenever you try to sync an Invoice to Xero when that number is already in use. 


  1. Edit the Invoice number in Clio to be unique
  2. Wait for sync to re-run


Was this article helpful?
This information is confusing or wrong
This isn't the information that I was looking for
I don't like this functionality