The Account Number already exists sync fault
This issue arises when a Xero customer has been assigned the same account number while also being marked as archived.
How to resolve
If you receive a error message from Cloud Depot - Invoice Fault! Xero reported a validation fault: The Account Number already exists
Access your Xero account, locate the archived contact, and unarchive it. Next, either remove or modify the account number, and then re-archive the contact.
Then issue a re-sync of the faulting invoice.