Install Joomla extensions from the Joomla admin itself: go to System > Manage > Install and either upload the extension's zip file directly or install from a URL. A few server-side settings determine whether a large extension upload succeeds or fails.
Installing an extension from the Joomla admin
Log in to your Joomla administrator panel (usually at yourdomain.com/administrator) and go to System > Manage > Install. You have three options on this screen:
- Upload Package File: drag in the zip file you downloaded from the Joomla Extensions Directory or a vendor site.
- Install from Web: browse and install directly from the Joomla Extensions Directory without leaving the admin.
- Install from Folder: point Joomla at a directory on the server where you've already extracted or uploaded the files, useful for large extensions you've placed via FTP or File Manager.
After installation, most extensions (components especially) need to be enabled and configured under Components in the admin menu, and plugins need to be enabled individually under System > Manage > Plugins. A plugin sitting installed-but-disabled is a common reason an extension appears not to work.
When the upload fails: PHP limits
If Joomla rejects a zip upload as too large, or the install hangs and times out, the cause is almost always a PHP limit, not Joomla itself. The two settings that matter are upload_max_filesize and post_max_size. On Flashcloud, these aren't changed from the portal's PHP Version tile, that tile only switches your PHP version (7.4 through 8.3). To raise upload limits, open cPanel from your service page and go to Software > MultiPHP INI Editor. Select your domain, switch to Editor mode, and raise both values, then save.
If the extension is large enough that even a raised limit doesn't help, skip the browser upload entirely: use File Manager (or FTP) to upload the zip to a temp folder, extract it there, then use Joomla's Install from Folder option pointed at that path.
Picking the right PHP version
Joomla releases are tied to specific PHP compatibility ranges, and a mismatch shows up as a white screen or a fatal error right after you activate a new extension. Check the extension's minimum PHP requirement against what your Joomla core version supports, then set the matching version from the portal's PHP Version tile on your service page. This is a per-domain setting, so if you run more than one Joomla site under the same account, each can run its own PHP version independently.
Caching and file permissions after install
Joomla ships its own page cache and system cache under System > Global Configuration > Cache. If a newly installed extension isn't showing its changes, clear Joomla's cache from there first, then clear any cache on your hosting account before assuming the install failed. See how we make your site fast for more on that layer.
Some extensions also need specific folders to be writable during install (for uploading media, generating configuration files, etc.). If an install reports a permissions error, use File Manager to check that the target folder has write permission for the site's hosting account.
Where Softaculous fits in
If you installed Joomla itself through Softaculous Apps Installer in cPanel, note that Softaculous manages the initial Joomla install, not individual extensions. Extension installs always happen inside the Joomla admin as described above. Before installing an extension you're unsure about, take a backup first (JetBackup 5 or the Backups tile in the portal) so you have a clean rollback point if something breaks the site.
When to contact support
If you've raised the PHP upload limits, confirmed the PHP version matches the extension's requirements, and the install still fails with a server-level error rather than a Joomla error message, open a ticket from the Support section in the portal. Include the exact error text and the extension name and version.