In case you use SSL with your website and you enabled Cloudflare, your website might go in a redirect loop.
This is because of how SSL Support is configured with Cloudflare. By default, it is set to 'Flexible'. Flexible means that SSL requests for your website will reach Cloudflare, and Cloudflare's servers will attempt to fetch your website over normal HTTP. If your website is configured to open up via HTTPS this can create a loop.
To resolve the issue you need to change SSL Support for your website from 'Flexible' to 'Full Strict'. In this way, after Cloudflare receive a secure request for your site, they will use another secure request over HTTPS to fetch it from its host server.
You can change the SSL Support settings from your cPanel -> Cloudflare -> Settings tab. Once you change the value, you need to allow a few minutes.
You can also read more about the different Cloudflare SSL Support options here.