The dark side of Joomla! caching

UPDATE! Bug has been confirmed and will be fixed in Joomla! 3.4.1

We've recently talked about the benefits of Joomla! caching. In the past weeks, we've seen an increase of people using Joomla! caching and that's a good thing - but not without its issues.

The setup

What most people don't realize is that when you enable caching in Global Configuration — for example when setting it to ON - Conservative caching, you will end up with non-working plugins. Let me exemplify:

Let's say you want to increase your website's security by installing RSFirewall!. By default, the RSFirewall! component also comes with a System Plugin called 'System - RSFirewall! Active Scanner'. Usually you'll need to manually activate the plugins you're installing on your website (by going to Extensions — Plugin Manager and publish the respective plugin), but for your convenience (and because RSFirewall! doesn't work without it) this plugin gets published automatically during installation.

What happens when you've enabled Cache?

Caching takes a snapshot of the current status of your plugins - which ones are published and which ones are not. Even if you manually enable or disable a plugin, the snapshot will not get refreshed. And since the default status when you install a plugin is unpublished, you'll end up with a non-working plugin on your website and you won't even know about it.

What can be done about it?

You'll have to go to System — Clear Cache — select Administrator from the left Filter bar — select all items — click Delete on the toolbar above. Or, you'll need to set Cache from Global Configuration to OFF - Caching disabled.