Why the Sync Error occurs
This error occurs when an account on the bill has been deleted or the connection has been broken. The deletion may have occurred in Bill.com or QuickBooks Online.
How to Fix the Sync Error
Check the Chart of Account(s) on the bill to verify that the account(s) has not been deleted. If needed, restore the deleted account(s).
If the account(s) on the bill/invoice is active, if the error continues after restoring, or if the bill/invoice is deleted in either Bill.com or QuickBooks, contact Customer Support.