If you are a CloudFlare user, there are a few things to consider when migrating to SSL. If you run into redirect loops when you use CloudFlare, and have activated Really Simple SSL, check if you have configured below settings correctly.
In CloudFlare you have the option to define page rules. If this page rule redirects all requests to http, activating Really Simple SSL will result in CloudFlare forcing your site to http, and Really Simple SSL forcing your site to https. A redirect loop is the result. You can remove the page rule, or change it into a page rule to https.
SSL settings in CloudFlare
If you have your own certificate, you should select Full SSL. If you use the CloudFlare SSL option, choose flexible SSL. Not selecting the correct option might cause redirect loops.
Make sure CloudFlare does not cache old data
When we migrate a CloudFlare website to SSL, we always start with turn development mode in CloudFlare on. When everything is ready, purge the cache, the turn off development mode.
If you have not purged CloudFlare cache, you might get mixed content on your site.
If you run into anything that is not covered here, please let me know!