When you experience a redirect loop, this can be caused by several things, I’ve listed the most common causes below.
Most checks can be done without access to the back-end. If these steps all fail, and you still have a redirect loop, you can try to activate Really Simple SSL in safe mode. This will activate Really Simple SSL without redirect and without your site url becoming https. If all fails you can always deactivate using the remove script, or manually.
A redirect back to http
This is the most likely cause, and you can check if this is the case by typing in your url with https (when Really Simple SSL is deactivated). If you get redirected back to http, there is a redirect to http active, which will cause redirect loops when a redirect to https is added.
- Check other plugins
- Multilanguage plugins,
- login plugins,
- redirect plugins
- WooCommerce with certain settings can redirect to http.
- Ithemes SSL settings
- Check if your .htaccess or nginx.conf contains redirects to http.
If you have other redirects in place, this could conflict with the redirect of Really Simple SSL.
Check if you have Varnish Cache active
Varnish often causes issues on SSL. Ask your hosting company if Varnish is active, and if they can disable it to see if that helps. With a service like www.redirect-checker.org/ you can see if your site uses Varnish Cache. If so, you should be able to deactivate Varnish in your webhosting dashboard, like CPanel.
Check your certificate
In some cases a certificate with chain issues can cause issues. Check if your certificate is ok on https://ssllabs.com/ssltest. It should at least grade an A.
CDN, like CloudFlare
For the most common issues with CloudFlare, see the dedicated CloudFlare article
Redirect loop on multisite with domain mapping
I’ve had reports that the WPMU domain mapping plugin in combination with Really Simple SSL can cause redirect loops. Although I haven’t been able to investigate the cause, I think the best solution is to follow the instructions in this article. In short: remove the wpmu domain mapping plugin, and map it using the built in capabilities of WordPress.