I have made further checks to the site and have found nothing which would give rise to the problems as related to your comments.
But for website with a lot of customization, it is always recommend to perform an update in a pre-prod website. To check it before the production.
I DO have a test site set up to try to avoid problems on upgrade (though I have consistent back-end messages to add this to my HikaShop account page - and presumably pay an additional license fee), but I did not expect to have any errors, because my edits are all made either in the CSS or view files. But having an 'original' version has enabled me to make some comparative screen shots.
1. When a menu item is created and saved without attaching an Associated module, a warning message appears (h29afd48.jpg below) offering to automatically link to an associated module. This has never been a requirement on the site in question because categories stand alone with no need for sub-categories to display below them. However, since updating to v2.3.1 (and there's v2.3.2 yet to be added!), HikaShop seems to
create and link associated module(s) by default (see h5eede84.jpg below), necessitating the removal of the associated category links and deletion of the unwanted modules (h3bdacdb.jpg below).
Why does this happen, since none of the menu items had an associated module selected prior to the update (see h23ce9dc.jpg below), in either the menu form page or the 'Modules main default options'?
2.
There is no change in the view.
There IS a change in the content displayed - compare h5bfa01d.jpg below, which is taken from my test (original) site and shows no products listed under the top level 'Product categories' (products were listed only under their related categories) with h765dac6.jpg, which shows ALL products listed under the top level after the v2.3.1 update, including the headers for selected custom fields. However, h2b5c3ac.jpg shows that the updated category product lists display none of the selected custom field headers set up in the original version (see h6623324.jpg below) and shown under the main Product category listing after upgrade.
Additionally, I had set up custom fields to appear on the product pages (hfcfe41c.jpg), but since the upgrade, none of my custom fields appear in the backend form (h2819b68.jpg), so are not available for any new product pages. Why is this? All the custom fields are present in the back-end, and correctly set up to display as required, but being absent from the product details, these custom fields can neither display, nor -
3. be searched for.
Fixing point 2 should help you for this point.
I am sure the search module is working properly, but
I cannot see why the custom fields (eg. h1145ab3.jpg) are not appearing or functioning as expected.
4. OK.
5. I repeat, the Changelog is extremely helpful, but customised view files are not overwritten, therefore could cause problems by not including HikaShop updates. Should I take the view code from your demo site, compare it to my site code and add any changes to retain my customisations
and any HikaShop updates? This would, at least, avoid the site being broken by new versions of HikaShop.
Further to this, the front-end view files which have my customisations and have therefore not been updated by the new version are:
address/address_template ; category/listing_img_title ; checkout/listing_price ; product/cart ; product/listing ; product/listing_img_title ; product/listing_price ; product/show_default.
Could the problems relate to any of these non-updated files?
Thank you.