In this commit, 1. Adding a safeguard to ensure date_from is not empty before calculating the time delta in the wizard.date_to. 2. Both classes disabled="1" and disabled="true" are not working so we add a disabled class on the button. I don't know why disabled="1" is not working. task-3328601 closes odoo/odoo#123148 X-original-commit: 97b8d59a88e78afbeae1dc6447a3d9629635524f Signed-off-by: Kevin Baptiste <kba@odoo.com>