Recently I installed Joomla! for a customer who is using HTTPS protocol. When trying to access the “Joomla! install from web,” I received the warning:
Error: Cannot connect to the Joomla! server. Please try again later.
I’m unsure if this bug has been fixed, but if you’re having this problem then try the following solution:
Open file plugins/installer/webinstaller/webinstaller.php.
On line ~21 you’ll find the following line of code:
public $appsBaseUrl = 'http://appscdn.joomla.org/webapps/';
There lies the problem. The file is trying to access the URL in HTTP mode and not HTTPS mode. The solution is to add an ‘s’ after ‘http’ so that your site can communicate with Joomla!’s server in https protocol.