Hello, good afternoon! I'm using Odoo to register several leads and structured the kanban pipeline as follows: new -> qualified -> proposition -> won. 

The idea is that when changing the stage to "won", Odoo retrieves the lead data and creates a subscription/invoice in the sales.order. I tried to develop some things, even with code, but it always returns the error:

The operation cannot be completed: 

Create/update: a mandatory field is not set. 

Delete: another model requires the record being deleted. If possible, archive it instead. 

Model: Sales Order (sale.order) 

Field: Customer (partner_id). 

Would anyone know how to provide some coding for this use?