This error notifies you of an incorrect setup of Xero.
To troubleshoot this error please follow the process bellow.
1/ Check that your AgriDigital and Xero accounts are mapped correctly.
You will find all the information to help you in this article: What do I need to do to set up my AgriDigital account for XERO Integration?
2/ Delete the associated invoice from Xero
The invoice you are trying to publish into Xero, might have a associated invoice for Royalties. In this case, this royalties invoice will already be present in your Xero account.
Please delete it from Xero.
3/ Manually publish your invoice to Xero
Once you are satisfied steps 1 and 2, you can manually publish your invoice into Xero.