Upgrade 2.2.0.0 to 2.3.0.2 and PHP compatability

I'm new here.
I am the content-administrator of an OpenCart based webshop, currently running 2.2.0.0.
Last week our hoster decided our PHP version (5.x) was too old, and switched our webhosting to 8.x.
This caused the site to crash / not work anymore.

Is it possible to upgrade to 2.3.0.2 without too much troubles? The main problem I'm facing is that the shop is running the CosyOne extension/template, which, as far as I can see, is no longer maintained/supported, and problably only is working on 2.x.

If we could get 2.3.0.2 running on our webhosting with PHP 8.x, that would buy us some time to later upgrade to a newer version.

This Version is able to work with PHP v.8.x
https://github.com/condor2/Opencart_230x_PHP_8

2.3.0.2 has a slightly different extension directory structure compared to 2.2.0.0. There is some backwards compatibility added, but how easy it is to upgrade would depend on your theme and extensions. 2.3.0.2 would probably not be any more compatible with PHP 8 than 2.2.0.0. If your site is not working upgrading to a later version of OpenCart is not usually the best option.

The easiest option is to see if your hosting has the option to select a lower and still maintained version of PHP in the control panel (or switch host to one that does).

It's usually not too much work to get a site working with PHP 8. It's usually a few minor change and possible upgrade of Twig, but again it would depend a lot on your theme and extensions.

Your OpenCart and PHP error logs may give clues to what to search for in the forums. You will also find a 3.0.x.x_Maintenance branch on GitHub that has fixes applied to 3.0.3.8 for PHP 3 compatibility.
https://github.com/opencart/opencart/tr ... aintenance

It seems the most issues causing the site to malfunction when switching to a newer PHP version, are caused by the CosyOne extension. Important parts of the look and feel (menu's, carousels etc) of the site seem to be coming of this extension.
So I guess we need to find us a more recent extension.
It probably also gives us the opportunity to update to 3.x or 4.x. Any thoughts on that? Should we upgrade to 3.x or 4.x?

Well, if you want to belong to the Problem-Finders, upload to the latest OC v.4.x, or then, get the latest OC v.3.x Version here, to get something known to work:
https://github.com/opencart/opencart/tr ... nce/upload

As IP_CAM suggested, probably best to go for the 3.0.x.x_Maintenance release. OpenCart 4 releases are still somewhat too buggy. Do a fresh install, don't use the upgrade functionality which in most cases will cause issues. You can copy your old product data to the new OC version via the Export/Import tool, see also our FAQ on this.

Thanks for your answers!
Via this export/import tool, are the user-accounts including credentials also saved?
I can understand the idea behind a fresh install, but I think I loose important settings, for example for the payment provider and such.
Since the site was developed by someone else (who's not really available anymore), and my experience with OpenCart is until now mostly limited to adding / removing products, I'd rather keep as much settings as possible.
The hoster gives me the possibility to do backups.
I'm planning to create a backup at the hoster, then disable this CosyOne extension, and then try upgrading to 3.x, to see what life's like at that point.

You can attempt to resolve the issue by disable and remove all extensions and upgrade.
If this doesn't resolve the problem, the next step would be to consider a fresh installation and then importing your old data into it.

I finally went with a fresh installation of the 3.0.3.8 maintenance release.
Did manage to backup/restore a lot of data with the import/export tool.
Furthermore restored some data via sql / phpmyadmin.
It was a lot of work, but it payed off.
The basic store is back online, and seems to work, that was the main goal at first.
Now looking for a nice theme on top of it.