QuickBooks Windows Sync Error: There was an error when saving a Bill. QuickBooks error message: This transaction action is not allowed for this user.

Why the Sync Error occurs

This error occurs when a bill is trying to sync to a closed period in QuickBooks.

Open the period in QuickBooks to allow the bill to sync ~ or ~
Update the invoice date on the bill in Bill.com, changing the date to one in an open period