opencart admin no image thumbs - opencart

Question

I'm using opencart ver 2.3.0.1 for a personal project, using Ubuntu 17.10 and I got a strange behaviour configuring the Apache server (Apache/2.4.27) or the admin/config.php files. I don't know, probably both.
The Catalog section is working just fine, but in the administrative (Admin) one, thumbs images are not displayed correctly. I mean, all menu functions are displayed correctly, but for example, in product section, the element thumbs are not displayed, nor the product image in its section. Using the "inspect" Chrome function I can see that the thumbs are pointing to an incorrect path:
This is the link showed in the inspect section:
<img src="image/cache/catalog/<dir>/<file-name>" alt="<name>" class="img-thumbnail">
When I pass the mouse over it, it display the complete path:
http://192.168.1.123>/<site-name>/admin/image/cache/catalog/<dir>/<file-name>
Here, the " /admin/ " element is the one that prevents the link working. The url should be:
http://192.168.1.123/<site-name>/image/cache/catalog/<dir>/<file-name>
as stated in admin/config.php:
define('DIR_IMAGE', '/var/www/html/<site-name>/image/');
The HTTP & HTTPS sections in admin/config.php:
// HTTP
define('HTTP_SERVER', '');
define('HTTP_CATALOG', '');
// HTTPS
define('HTTPS_SERVER', '');
define('HTTPS_CATALOG', '');
And the .conf in /etc/apache2/sites-available/
<VirtualHost *:80>
ServerAdmin <email>
DocumentRoot /var/www/html/<site-name>
ServerName <site-name>
ServerAlias www.<site-name>
<Directory /var/www/html/<site-name>/>
Options FollowSymlinks
AllowOverride All
Order allow,deny
allow from all
</Directory>
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
How can I configure correctly the opencart admin section? I tryied so many combinations but I can't figure the reason for this behaviour. Thanks!

Answer 1

As expected, as I wrote for help, 5 minutes after I got the the solution:
The issue is caused because of cross-domain policies when the frontend or the admin panel are accessed from a different address than the one configured in the OpenCart config files. For example, if you have installed your OpenCart for the address http://address but you access your site via http://www.address you will experience such issue. The solution to this is fairly simple. Open config.php file from OpenCart root folder as well as config.php from the admin folder and make sure HTTP_SERVER and HTTPS_SERVER point to www location. For example:
config.php - OpenCart root folder
// HTTP
define('HTTP_SERVER', 'http://www.example.com');
// HTTPS
define('HTTPS_SERVER', 'http://www.example.com');
config.php - OpenCart admin folder
// HTTP
define('HTTP_SERVER', 'http://www.example.com/admin/');
define('HTTP_CATALOG', 'http://www.example.com/');
// HTTPS
define('HTTPS_SERVER', 'http://www.example.com/admin/');
define('HTTPS_CATALOG', 'http://www.example.com/');
I'm letting this here in case could help...
Bye!