Steps to reproduce the bug: Go to a work order that is ready or waiting, try manually changing the scheduled start or end date > save Problem: Traceback is triggered because when we modify the date, we check if the start date is before the end date. But we cannot compare a False with a date opw-2768054 closes odoo/odoo#85991 X-original-commit: 1768a072fd40d14dc8c402c3ccad9a6733460c03 Signed-off-by: William Henrotin (whe) <whe@odoo.com> Signed-off-by: Djamel Touati (otd) <otd@odoo.com>