The name of your first customer invoice is a configuration that determines the next ones. The problem before is that when you confirmed a first invoice, you could not alter its document number anymore. With this commit, as long as it is the first invoice, you can still change the document number when you reset to draft. closes odoo/odoo#65341 Related: odoo/enterprise#16058 Signed-off-by: Josse Colpaert <jco@openerp.com>