Magento – Website is stuck in redirect loop

Based on the hints by Simon, here is what I have:

1) Make sure "Auto-redirect to Base URL = No". It was set to "yes", and causing the problem.

2) Put the below in the .htaccess:

RewriteCond %{HTTPS} off
 RewriteCond %{HTTP_HOST} !^www\.(.*)$ [NC]
 RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

 RewriteCond %{HTTPS} on
 RewriteCond %{HTTP_HOST} !^www\.(.*)$ [NC]
 RewriteRule ^(.*)$ https://www.%{HTTP_HOST}/$1 [R=301,L]

 RewriteCond %{SERVER_PORT} !^443$
 RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]

It works for me, at least for now.

Please also update

System > Configuration > General > Web > Unsecure > Base URL

It should be https://www.example.com/ And add this code in .htaccess

#enable website to run https 
        RewriteCond %{HTTPS} off
        RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

And flush your Magento cache. For "Blocked loading mixed active content" open firebug console, it will tell which file is causing this error. If you are using static URL then you need to change it manually from http:// to https:// for more information on this visit here.