After the upgrade, not all old modules may work properly.
If a module used override, it may not be compatible with the new version of Prestashop.
You can also cause this problem by using an upgrade module, of which there are many, but they have many bugs.
So I personally do not recommend upgrading from 1.6 to 1.7 any module, but use a clean installation and only then import data from the old version of Prestashop.
It is necessary to realize that each new version of Prestashop also has database updates, for example some tables are deleted and some are added.
80% of module programmers make the mistake of not updating their module for the new version of Prestashop.
It writes into the module from which version of Prestashop the module will work, but does not write exactly into which version its module will work, but writes the general condition that it is always compatible with the current version of Prestashop. And there are problems in the world.
E.g.
https://devdocs.prestashop.com/1.7/modules/creation/tutorial/
if (!defined('_PS_VERSION_')) { exit; }
....
....
...
BAD
$this->ps_versions_compliancy = array('min' => '1.6.0.1', 'max' => _PS_VERSION_)
OK
$this->ps_versions_compliancy = array('min' => '1.6.0.1', 'max' => '1.6.1.24')