htaccess Redirect All Traffic to https

Question

I'm a beginner when it comes to doing stuff with htaccess so please be patient with my dumb question. I know that this has been addressed a lot (here, here, and here for example) but it doesn't seem to work for my situation. My browser displays a "redirect loop" error with this code in my htaccess file:

<IfModule mod_rewrite.c>
    <IfModule mod_negotiation.c>
        Options -MultiViews
    </IfModule>

    RewriteEngine On

    # Redirect Trailing Slashes...
    RewriteRule ^(.*)/$ /$1 [L,R=301]

    # Handle Front Controller...
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^ index.php [L]

    # Trying to redirect to https
    RewriteCond %{HTTPS} off
    RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}
</IfModule>

I know that this probably has something to do with the RewriteCond and the RewriteRule before I redirect to https, but I don't really know what I'm doing here and I don't know what to change.

Update:

Some more info that might be helpful:

1. When I remove the "redirect to https" code and manually type https://my.site.com it loads just fine.
2. Also, the redirect-to-https thing worked great before I accidentally deleted the .htaccess file in my directory.

3. The app that I'm trying to redirect resides in a subfolder of another app which also has an .htaccess file. Here's the code for that app:

   <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.php [L] RewriteEngine On </IfModule>

This is what firebug says:

Answer 1

Change order of your rules and keep 301 rules before other internal rewrite rule:

<IfModule mod_rewrite.c>
    <IfModule mod_negotiation.c>
        Options -MultiViews
    </IfModule>

    RewriteEngine On

    # Redirect Trailing Slashes...
    RewriteRule ^(.*)/$ /$1 [L,R=301]

    # Trying to redirect to https
    RewriteCond %{HTTPS} off
    RewriteCond %{SERVER_PORT} !=443
    RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,NE,R=301]

    # Handle Front Controller...
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^ index.php [L]

</IfModule>