Free access to page 404.html with . htaccess

Question

I am having a problem when trying to free access to 404.html page through my . htaccess, always gives Internal Server Error. How should I apply a rule to only 404.html is released for direct access?

.htaccess:

Options -Indexes
RewriteEngine On

RewriteCond %{REQUEST_FILENAME} -s [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d

RewriteRule ^.*$ - [NC,L]

RewriteRule ^([^/]*)$ index.php?page=$1 [L]
RewriteRule ^([^/]*)/([^/]*)$ index.php?page=$1&sub=$2 [L]
RewriteRule ^([^/]*)/([^/]*)/([^/]*)$ index.php?page=$1&sub=$2&id=$3 [L]

<Files *.php>
    Order Deny,Allow
    Deny from all
    Allow from 127.0.0.1
</Files>

<Files index.php>
    Order Allow,Deny
    Allow from all
</Files>

Answer 1

You can try this way:

Options -Indexes
RewriteEngine On

RewriteCond %{SCRIPT_FILENAME} !-f
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteRule ^([^/]*)$ index.php?page=$1 [L]

RewriteCond %{SCRIPT_FILENAME} !-f
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteRule ^([^/]*)/([^/]*)$ index.php?page=$1&sub=$2 [L]

RewriteCond %{SCRIPT_FILENAME} !-f
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteRule ^([^/]*)/([^/]*)/([^/]*)$ index.php?page=$1&sub=$2&id=$3 [L]

<Files *.php>
   Order Deny,Allow
   Deny from all
   Allow from 127.0.0.1
</Files>

<Files index.php>
   Order Allow,Deny
   Allow from all
</Files>

eliminating the RewriteRule ^.*$ initial, to only redirect if there is no corresponding file (remembering that each set of RewriteCondonly goes to the RewriteRule next).

See more in this answer:

Rewrite URL for "root" accesses but do not block access to sub-domains