/index.php essential?

[picandnix]

Apologies for the delay.

	## BEGIN CEON URI MAPPING REWRITE RULE
RewriteEngine On

# Don't rewrite any URIs ending with a file extension (ending with .[xxxxx])

RewriteCond %{REQUEST_URI} !\.[a-z]{2,5}$ [NC]

# Don't rewrite any URIs for some, popular specific file format extensions,

#   which are not covered by main file extension condition above

RewriteCond %{REQUEST_URI} !\.(mp3|mp4|h264)$ [NC]

# Don't rewrite any URIs for some specific file format extensions,

#   which are not covered by main file extension condition above

#   Uncomment the following line to apply this condition! (Remove the # at the start of the next line)

#RewriteCond %{REQUEST_URI} !\.(3gp|3g2|h261|h263|mj2|mjp2|mp4v|mpg4|m1v|m2v|m4u|f4v|m4v|3dml)$ [NC]

# Don't rewrite admin directory

RewriteCond %{REQUEST_URI} !^/mysecretadmin [NC]

# Don't rewrite editors directory

RewriteCond %{REQUEST_URI} !^/editors/ [NC]

# Don't rewrite min directory

RewriteCond %{REQUEST_URI} !^/min/ [NC]

# Don't rewrite DELETEdownload directory

RewriteCond %{REQUEST_URI} !^/DELETEdownload/ [NC]

# Don't rewrite languages directory

RewriteCond %{REQUEST_URI} !^/languages/ [NC]

# Don't rewrite functions directory

RewriteCond %{REQUEST_URI} !^/functions/ [NC]

# Don't rewrite cgi-bin directory

RewriteCond %{REQUEST_URI} !^/cgi\-bin/ [NC]

# Don't rewrite logs directory

RewriteCond %{REQUEST_URI} !^/logs/ [NC]

# Don't rewrite auto_loaders directory

RewriteCond %{REQUEST_URI} !^/auto_loaders/ [NC]

# Don't rewrite setup directory

RewriteCond %{REQUEST_URI} !^/setup/ [NC]

# Don't rewrite classes directory

RewriteCond %{REQUEST_URI} !^/classes/ [NC]

# Handle all other URIs using Zen Cart (its index.php)

RewriteRule .* index.php [QSA,L]

## END CEON URI MAPPING REWRITE RULE

[picandnix]

This line the issue?
RewriteRule .* index.php [QSA,L]

[mc12345678]

This line the issue?
RewriteRule .* index.php [QSA,L]

Sort of... let me explain. That line is what to do if all of the rewritecond (conditions to be met to support the rewrite rule) lines above check out as true... so, with the way it is currently testing, nothing specifically says: hey this is a demo site that is trying to be reached (or reverse, this isn't the main site that is trying to be reached) and then preventing the rewrite rule from taking action...

But if you add:

RewriteCond %{HTTP_HOST} ^www.mydomain.com$ [OR]
RewriteCond %{HTTP_HOST} ^mydomain.com$

Somewhere above the rewriterule (but also after a previous rewriterule if there were one) and below the rewriteengine on statement then, if demo.mydomain.com is accessed, the uri will not be rewritten from the root domain when trying to access the sub-domain...

[buildingblocks]

sounds like what I've encountered a number of times when installing a test cart to a sub-domain or sub-folder when the top domain cart is using ceon uri installed. Adding

RewriteEngine Off

to the .htaccess file of the cart in the sub folder or sub-domain stopped the problem