QuickBooks Online sync error: Bill/Invoice number is being used on another bill from the same vendor. Use a unique invoice number for the vendor bill.

Why the sync error occurs

This error occurs when a new bill or invoice is trying to sync from Bill.com to QuickBooks Online, but the invoice number is already in use for that vendor or customer in QuickBooks Online.

How to fix the sync error

You can fix this error in a few ways:

  • Edit the invoice number in Bill.com to be unique for that customer or vendor
    • You won't be able to edit the invoice number if the bill is paid
  • Edit the invoice number: find the existing bill or invoice in QuickBooks Online that has the same invoice number as the bill or invoice in the sync error, and change the invoice number to be unique
  • If you can't change the invoice number in QuickBooks Online or Bill.com, contact Customer Support for assistance