Hi there,

Actually you need a custom behavior that shows warning message to user than make some data changes but when you raise errors 

cursor goes brrrrrrrr then rollback.. :D

So just create a wizard to show warning;

model:

class CustomPopup(models.TransientModel):
    _name = 'module_name.cpup'
    _description = 'Custom Popup'
    _rec_name = 'title'

    # ----------------------------------------
    # Main Information
    # ----------------------------------------
    title = fields.Char(string='Title')
    description = fields.Text(string='Description')

view:
<!--Custom Popup Form View -->
<record model="ir.ui.view" id="custom_popup_wizard_form">
    <field name="name">module_name.custom_popup</field>
    <field name="model">module_name.cpup</field>
    <field name="arch" type="xml">
        <form string="Popup" create="0">
            <sheet>
                <div class="oe_title">
                    <div class="o_notification_box mb0 alert alert-dismissible alert-info"
                         role="status">
                        <a class="close" data-dismiss="alert" href="#">x</a>
                        <i class="fa fa-info-circle fa-3x text-info float-left"
                           style="padding-right: 15px;" role="img" aria-label="Info"
                           title="Info"/>
                        <h4 class="alert-heading" role="status"> <field name="title"/></h4>

                        <hr/>
                        <p class="mb-0">

                            <strong>
                                <field name="description"/>
                            </strong>
                        </p>
                    </div>
                </div>
            </sheet>
        </form>
    </field>
</record>


Then create an instance from this wizard;
where u raise the error then make your database thinks after this;

created_popup = self.env['module_name.cpup'].create({'title':'WOW DUDE SLOW DOWN!','description':'Life goes on ..'})
return {
    'name': _('Somethink Went Wrong'),
    'type': 'ir.actions.act_window',
    'view_mode': 'form',
    'res_model': 'module_name.cpup',
    'res_id': created_popup,
    'target': 'new'
}