apache $1 failed when file exist on public_html - .htaccess

Question

i have a simple htaccess with a simple rewrite rule
AddDefaultCharset UTF-8
#
# page.php
#
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^page/([^.]+)?$ page.php?slug=$1 [L,NC,QSA]
I use this rule to show static pages for a long time.
The last few months this simple rule is not working in some servers (cPanel and VirtualMin) and don't understand where the problem is.
The rule make the match and execute page.php script which is located in public_html but the slug variable is null.
I have found that if i rename the page.php to _page.php its working fine.
To be more clear
if the bold matches i get no slug
page/([^.]+)?$ page.php?slug=$1
if i use
_page/([^.]+)?$ page.php?slug=$1
page/([^.]+)?$ _page.php?slug=$1
page/([^.]+)?$ page99.php?slug=$1
everything works fine.
Of course i have and other rules that are working fine.Only this rule is failed.
Any help appreciated

Answer 1

It looks like MultiViews is probably enabled on these servers where it is not working (ie. the slug URL parameter is missing).
Disable MultiViews at the top of your .htaccess file:
Options -MultiViews
MultiViews is disabled on a default Apache install, however, some shared hosts do enable this in the server config for some reason.
MultiViews basically enables extensionless URLs out of the box. When MultiViews is enabled and you request /page (or /page/<something>) then mod_negotiation looks for a resource that maps to the same basename (ie. page) that would return the appropriate mime-type (ie. text/html). In other words it would look for files of the form page.php or page.html etc. This occurs before mod_rewrite is able to process the request, so the URL parameter (in your mod_rewrite directive) is missing, because the RewriteRule did not get processed (it doesn't match).
I have found that if i rename the page.php to _page.php its working fine.
Yes, because the requested URL page does not map to the basename of a physical file.