1.) Navigate to your joomla's plugins/installer/webinstaller/webinstaller.php file

2.) change:


public $appsBaseUrl = 'http://appscdn.joomla.org/webapps/'; // will be https once CDN is setup for SSL

         to:

public $appsBaseUrl = 'https://appscdn.joomla.org/webapps/'; // will be https once CDN is setup for SSL