Odoo - ParseError:“ValidateError字段“arch”在约束下失败:无效的视图定义

I'm following a tutorial on Odoo and I have to create a new view to easily create/edit payment methods. Adding the many2one field in Sales Order works but once i add the xml lines given in the tutorial and upgrade it gives an error. Restarting the service results in an Internal Server Error.I'm following a tutorial on Odoo and I have to