Discovered - akeeba/onthos GitHub Wiki

Why is it a problem?

The extension's files are present on your site, but this is not enough for an extension to be installed. An extension must go through Joomla's extensions installer to create the necessary database records and update Joomla's internal PHP namespace cache. Without these steps the extension cannot be used.

Suggested fix

If the extension was meant to be installed, click the “Open the Discover page” to go to Joomla's System, Install, Discover page filtered by this extension. Select the extension and click on Install to finish installing it in Joomla!.

If this is a leftover extension –for example, the files are left over after restoring a backup on top of a different version of your site– click the “Force Uninstall” button to remove the extension's files from your site.

Notes

You should avoid using Discover to install extensions.

The Discover method dates back to the ‘olden days’ of Joomla where two things were common: single extensions, and badly configured servers. We're talking about the early years, before 2011, back in the Joomla! 1.0 and 1.5 times.

It was common to have software for Joomla! which consisted of a single extension, e.g. just one component, or just one plugin. These days extensions usually come in packages which contain multiple extensions, e.g. a component, and several plugins and modules. The Discover page can only install single extensions. This can cause problems; for an example see Orphaned.

Further to that, the necessity for the Discover page was down to badly configured servers which did not allow PHP to write to files on the server. This was a legitimate issue back in the days of shared hosting before suPHP, PHP-FPM, and virtualization / containerization were a thing. These days you have to actually try really hard –or follow an asinine server configuration tutorial vomited out by an LLM (“AI”)– to end up with a server that badly configured. Back in the day, we had to upload extension files manually over FTP to work around these restrictions. Therefore, in most cases, you can simply use Joomla's extensions installer pages to install extensions without having to upload files manually, making the Discover method a thing of the past.

As a result, the majority of Discovered extensions nowadays tend to be leftovers, therefore extensions with this issue should be treated with suspicion. If you are not sure whether you need this extension, install the package you suspect contains it twice in a row, without uninstalling it before or in between. If the extension continues to appear as Discovered chances are it's no longer needed, therefore its files can be removed.