Extension sort-by-date causes Undefined property

Hi,

Thank you for your report of the issue.
Indeed, it comes from issues.joomla.org/tracker/joomla-cms/38970
The issue is a combination of factors:
- until recently, it was totally ok to not provide that information in the XML
- Joomla doesn't have a check to make sure the the data is present in the XML before using it
- The warning only appears on PHP8 and above. Before, no error was displayed and thus it was not an issue

I've made a patch on our end to provide that information during the installation process (it's now available in the HikaShop install package on our website). This will remove the warnings for the plugins embedded with HikaShop. However, it will only work on new installations. When HikaShop is already installed, and the plugins already added to Joomla, HikaShop won't install the plugins and thus you won't see a change.

Hi,

Well, the simplest would be to uninstall HikaShop and uninstall all the plugins / modules included in HikaShop if it's not already done by the uninstall process.
Once that's done, install again HikaShop with the new install package with the patch I made and it will add back all the plugins and modules with the data in the database to avoid the error.
Normally, you shouldn't loose any data when doing so since the hikashop tables in the database won't be touched by all this. However, you will loose the settings of your plugins/modules so you'll have to reconfigure them.
I would recommend to try it on a copy of the website first, just to make sure that there are no surprises since no one did this yet.
Adding the missing data in the database manually is complex so I don't recommend trying it. You'll waste your time.