Installer should check for Joomla/CMS version compatibility
The install process checks system requirements. One of those requirements should be the CMS version.
- Install an older version of Joomla (eg 3.7.4)
- Install a recent version of CiviCRM (eg 5.22.1)
- Do something with Civi (eg create a contribution page and try to view the public side)
The install succeeds - but then things randomly fail. (In my case, public-facing Civi pages would fail with "Class 'Joomla\CMS\Factory' not found ".)
During installation, it should complain if your version of the CMS is too old to run this version of Civi.
I inadvertently stepped into this edge-case - I used the
joomla CLI tool to download the
latest release (
joomla site:download . --release="latest" --www="$PWD/web"), but it actually gave me a much older version... because
joomla had cached some very old metadata. That edge-case isn't a Civi issue... but the behavior of the installer on unsupported versions is...