How to upgrade from Ver 2.1.0.2 TO Ver 4.0.2.3

Please can someone help in providing instructions on how to Upgrade OpenCart v2.1.0.2 TO the latest - 4.0.2.3

I have opencart installed and running on my website, but it is a very old version. The hosting website is now upgrading their Server PHP platform from ver 5 to ver 8, and therefore my opencart installation that it hosts also needs upgrading.

I have downloaded and extracted the latest Install ZIP file, and read the instructions for installing - however, this looks like a FRESH install. How can the PHP files be UPGRADED without losing the current database/store configuration.

The guide does not seem to speak about this, unless it is something I have overlooked.

I would be very grateful if someone could explain and point me in the right direction.

Thank you!
Regards,
Donna.
14-12-23

Opencart 4.0.x.x is not stable for production. Better upgrade to 3.0.3.9 and wait for a stable oc 4 version.

You will most likely not be able to upgrade your OC Version, if you're not a professional OC Coder. Better read this about it first, and then decide on what to do about it:
viewtopic.php?t=231247#p856598

Thanks for taking the time to comment. Cheers Donna