When it comes to updates there’s often two thoughts I see
- Any add-ons/extensions/mods are only compatible with specific versions. Known as it worked on 2.5, why doesn’t it work on 3.0.
- Future versions try to maintain previous behavior and method signatures. Known as we require version 2.5 or newer.
With the announcement of Joomla 4 beta 1 I am once again thinking back to every previous major version upgrade and what that has meant. My first experience with this was when Joomla! 2.5 came out, which wasn’t an upgrade as much as a full blown migration. As luck would have it, Matware released jUpgrade which migrated content, menus, and related items to a new Joomla! 2.5 install. This was a life saver, and after using it once I made it part of my list when upgrading a site.
Now upon opening that new Joomla! 2.5 site, all your extensions now had to be installed, if a version for Joomla! 2.5 existed, and your templates (if they had just about any level of custom integration it seems) all had to be installed, after an update by the template provider to support Joomla! 2.5. This is what lead me to develop the very small BSC Article Footer, as I couldn’t find a replacement for a Joomla! 1.5 plugin so I decided I could write my own.
With Joomla! 3 the situation became a bit better, now you could upgrade from Joomla! 2.5 without a third party extension. Yet there was still some issues, so for this my list had the very critical step of disabling all extensions as I often got fatal PHP errors after most upgrades. Now it was disable all extensions -> upgrade Joomla! -> install updated extensions/templates -> re-enable each extension one by one to ensure none was missed. With this version I had some templates where they worked just as is, this was great. All custom extensions I had written did require some minor changes, as I now needed to use JControllerLegacy/JModelLegacy/JViewLegacy with a few other tweaks.
Now that Joomla 4 beta 1 is out, it now starts over again, only we know from the start that Joomla! 3.9, when released will have 2 years of support, which will give plenty of time for extensions to be updated.
While I can’t help but contrast this with WordPress’s situation, where I’ve often been able to use most extensions between updates, and with the use of a child themes, even keep the same theme thought an upgrade. Which is not without faults as talked about by WP Rocket in Backward Compatibility – Is It A Good Idea?