.htaccess lowercase rewrite causes HTTP error - apache

Question

I'm trying to write an .htaccess rewrite based on modified code from here that will convert URLs like this:
http://eXAMplE.CoM/sOMe-PatH/aNOTHer-PAth/FILEName.eXT
To this:
http://example.com/some-path/another-path/FILEName.eXT
Basically converting the entire URL to lowercase and excluding the filename.
[PROBLEM]
My .htaccess seems to be working OK with one exception: When anything beyond the initial path includes a capital letter, it results in no data from the server. I assume it's causing an infinite loop but can't be sure because I can't access the logs.
To clarify, this works:
http://eXAMplE.CoM/sOMe-PatH/FILEName.eXT
This does not:
http://eXAMplE.CoM/sOMe-PatH/aNOTHer-PAth/FILEName.eXT
Here is my code. Can anyone help?
RewriteEngine On
RewriteBase /
# Skip this entire section if no uppercase letters in requested URL
RewriteRule !.*?[A-Z].*\/.* - [S=28]
# Replace single occurance of CAP with cap, then process next Rule.
RewriteRule ^([^A]*)A(.*\/.*)$ $1a$2
RewriteRule ^([^B]*)B(.*\/.*)$ $1b$2
RewriteRule ^([^C]*)C(.*\/.*)$ $1c$2
RewriteRule ^([^D]*)D(.*\/.*)$ $1d$2
RewriteRule ^([^E]*)E(.*\/.*)$ $1e$2
RewriteRule ^([^F]*)F(.*\/.*)$ $1f$2
RewriteRule ^([^G]*)G(.*\/.*)$ $1g$2
RewriteRule ^([^H]*)H(.*\/.*)$ $1h$2
RewriteRule ^([^I]*)I(.*\/.*)$ $1i$2
RewriteRule ^([^J]*)J(.*\/.*)$ $1j$2
RewriteRule ^([^K]*)K(.*\/.*)$ $1k$2
RewriteRule ^([^L]*)L(.*\/.*)$ $1l$2
RewriteRule ^([^M]*)M(.*\/.*)$ $1m$2
RewriteRule ^([^N]*)N(.*\/.*)$ $1n$2
RewriteRule ^([^O]*)O(.*\/.*)$ $1o$2
RewriteRule ^([^P]*)P(.*\/.*)$ $1p$2
RewriteRule ^([^Q]*)Q(.*\/.*)$ $1q$2
RewriteRule ^([^R]*)R(.*\/.*)$ $1r$2
RewriteRule ^([^S]*)S(.*\/.*)$ $1s$2
RewriteRule ^([^T]*)T(.*\/.*)$ $1t$2
RewriteRule ^([^U]*)U(.*\/.*)$ $1u$2
RewriteRule ^([^V]*)V(.*\/.*)$ $1v$2
RewriteRule ^([^W]*)W(.*\/.*)$ $1w$2
RewriteRule ^([^X]*)X(.*\/.*)$ $1x$2
RewriteRule ^([^Y]*)Y(.*\/.*)$ $1y$2
RewriteRule ^([^Z]*)Z(.*\/.*)$ $1z$2
# If there are any uppercase letters, restart at very first RewriteRule in file.
RewriteRule .*?[A-Z].*\/.* - [N]
# Force a redirect with the new lowercase URL.
RewriteRule (.*) $1 [R=301,L]
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]
RewriteBase /
RewriteRule ^index\.php$ - [L]
# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]
# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]
</IfModule>

Answer 1

You'll be better off using RewriteMap instead. In the server configuration (or VHost configuration) add the following:
RewriteMap to_lower int:tolower
Now, you can use the function to_lower in your rewrite rules. Give the following a try:
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^((?=[A-Z]).+)(/[^/]+)$ /${to_lower:$1}$2 [R=301,L]