I have installed product_seo app : this link 

https://www.odoo.com/apps/modules/11.0/product_seo/

 but in show product page , i get this error

Traceback (most recent call last):
  File "/opt/odoo/odoo11/odoo/addons/base/ir/ir_http.py", line 208, in _dispatch
    result = request.dispatch()
  File "/opt/odoo/odoo11/odoo/http.py", line 830, in dispatch
    r = self._call_function(**self.params)
  File "/opt/odoo/odoo11/odoo/http.py", line 342, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/opt/odoo/odoo11/odoo/service/model.py", line 97, in wrapper
    return f(dbname, *args, **kwargs)
  File "/opt/odoo/odoo11/odoo/http.py", line 335, in checked_call
    result = self.endpoint(*a, **kw)
  File "/opt/odoo/odoo11/odoo/http.py", line 937, in __call__
    return self.method(*args, **kw)
  File "/opt/odoo/odoo11/odoo/http.py", line 515, in response_wrap
    response = f(*args, **kw)
  File "/opt/odoo/odoo11/addons/product_seo/controllers/controllers.py", line 16, in product
    active_id=product.id,
AttributeError: 'str' object has no attribute 'id'