Assuming you upgraded it to the latest software as a "dry run" rather than because of any actual need to upgrade it, given the archived status of the forum?
No actually. Yes, it is a useful exercise as a dry-run, but that wasn't the primary motivator. Old software becomes unsupported, which means that it no longer receives any upgrades or security fixes.
What's more, the forum software doesn't operate in isolation - the actual tech stack required to run a forum is as follows:
- forum software (XenForo)
- programming language (PHP)
- CGI process manager (PHP-FPM)
- web server (Nginx)
- database server (MySQL)
- cache server (Redis/Memcached)
- operating system (Ubuntu)
- virtual machine (KVM)
- physical hardware
... plus a whole heap of other supporting software and systems which go into running a complex site like this.
The problem arises when the underlying elements change - for example, a new version of the operating system is released and ships with a higher version of MySQL or PHP, which turns out to be incompatible with the forum software.
That's what has happened here. The version of XenForo we currently use is no longer supported - meaning the developers won't release updates or even security fixes for it. It also doesn't support the latest version of PHP which is now standard on the latest version of the operating system we use - so I can't upgrade the operating system without upgrading the forum software (well, I could - but it introduces quite a bit more complexity and risk).
XenForo 1.5 was released nearly 5 years ago and stopped receiving updates more than 1 year ago. To continue running this old version, we would have to keep our tech stack on supported versions - which means not upgrading them either, despite the fact that there may be security issues.
We need to update the forum software so that we can update the programming language so that we can update the operating system and all the other components we run on, etc.
It is of course possible to continue running old software on an old stack - but eventually things will stop working.
It's kind of like buying a house. You don't need to spend any time or money maintaining it - but if you don't, it will eventually fall down. Own a house long enough and the wiring and plumbing and roofing and internal fixtures will all need replacing at some point.
Software requires maintenance too because it does not exist in a vacuum - it interacts with other components and over time will need to be updated. Also, the longer software exists - the more likely that hackers will find a weakness they can exploit.
As a bonus, the newer versions of everything run much faster - so we get improvements from upgrades too. Actually, the most important thing to come out of this upgrade for me is that the forum software upgrade process has now been automated (basically one click updates), which is going to make it much easier for me to maintain the site going forward.
In this specific case, the old site was hosted in Singapore (the closest I could get to Australia at the time), but now the hosting provider I use has a data centre in Australia. So I built a new server in Australia running the latest software versions - Ubuntu 20.04, MySQL 8.0 and PHP 7.4 - but I couldn't move any of my forums to that new server until they were upgraded to the latest version too, which is what I've been doing.
For reference, ZooChat runs on a separate server in Newark, New Jersey - once I'm ready to upgrade ZooChat later this year, I'll build a new server running the latest versions of everything for it as well.