FUNCTION

@api.onchange('stage_id')
    def marcar_actividades_hechas(self):
        print("Entra Aquí")
        self.env['mail.activity'].sudo().search([('res_id', '=', self._origin.id)]).action_done()


ERROR

Odoo Server Error
Traceback (most recent call last):
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\http.py", line 651, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\http.py", line 310, in _handle_exception
    raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\tools\pycompat.py", line 87, in reraise
    raise value
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\http.py", line 693, in dispatch
    result = self._call_function(**self.params)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\http.py", line 342, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\service\model.py", line 97, in wrapper
    return f(dbname, *args, **kwargs)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\http.py", line 335, in checked_call
    result = self.endpoint(*a, **kw)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\http.py", line 937, in __call__
    return self.method(*args, **kw)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\http.py", line 515, in response_wrap
    response = f(*args, **kw)
  File "c:\program files (x86)\odoo 11.0\server\odoo\addons\web\controllers\main.py", line 934, in call_kw
    return self._call_kw(model, method, args, kwargs)
  File "c:\program files (x86)\odoo 11.0\server\odoo\addons\web\controllers\main.py", line 926, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\api.py", line 689, in call_kw
    return call_kw_multi(method, model, args, kwargs)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\api.py", line 680, in call_kw_multi
    result = method(recs, *args, **kwargs)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\models.py", line 5195, in onchange
    record._onchange_eval(name, field_onchange[name], result)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\models.py", line 5022, in _onchange_eval
    process(method_res)
  File "C:\Program Files (x86)\Odoo 11.0\server\odoo\models.py", line 4999, in process
    if res.get('value'):
AttributeError: 'list' object has no attribute 'get