This can be caused by your server configuration, or by the SSL certificate. Read this article on how to check if this is caused by your certificate. For possible causes related to server configuration, you can try the steps below.

On some servers, Safari may have issues with certain .htaccess redirects. To solve this, you can either remove the .htaccess redirect by:

1. Activating “stop editing the .htaccess” in the Really Simple SSL settings
2. Deleting the Really Simple SSL comments from the .htaccess

Or you can try different .htaccess rules. I’ve had reports that the following did work in one such case:

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

Though this is certainly not a best practice, and will not work always.

If you come across this issue, please let me know if this worked for you or if you found a different solution.