Hi Handoyo,
Thanks for your reply. I finally had a chance to try this, but it didn't work.
I changed the prefix as you suggested, but once I tried to run the upgrade via the Dashboard it took me to the "Critical Error" default page.
I thought it may be because I had to change the prefix in the "config.php" file as well, but I tried again and got the same critical error page.
I logged back in and it still shows Abantecart 1.2.1.
What if I try to do a completely fresh install of 1.2.3, then once the new database is created, drop it, and import the previous database?
I understand I'll have to change the salt key, and other settings in "config.php", etc. I'm just wondering if this is a good workaround for whatever is causing these upgrade errors.
Let me know what you think.
Thanks.