OC 2.3: Mixed content error in admin login blocking login

I have read multiple threads related to HTTPS and SSL before posting here and has already done suggested changes.

I just installed OC 2.3 on php 7.2 and tried to login into admin panel, but it is just refreshing the page.
I checked both config.php and both are correctly stating 'https', hence no changes were required on the same.

Now what can I do to fix this. In browser console, it is showing 'Mixed Content Error'. I verified on chrome as well as firefox.
Please guide.

Make sure, to have the config.php files looking like here:
viewtopic.php?f=190&t=220289

Hi,

I verified the config.php
HTTP and HTTPS both are mapped to https.

<?php
// HTTP
define('HTTP_SERVER', 'https://DOMAIN.in/products/');

// HTTPS
define('HTTPS_SERVER', 'https://DOMAIN.in/products/');

Store URL?