Mod rewrite not working on apache2 - apache

Question

I work on apache2 server. I am trying to display webpages on my website without the file extension .php using the following .htaccess file:
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php
# 1 ---- Establish a custom 404 File not Found page ----
ErrorDocument 404 /filenotfound.php
# 2 ---- Prevent directory file listing in all of your folders ----
IndexIgnore *
It is simply not working. I still see my webpages with .php extension in my browser.
I have mod rewrite module loaded and also I made changes in apache2.conf file as follows:
<Directory />
Options FollowSymLinks
AllowOverride None
Require all denied
</Directory>
<Directory /usr/share>
AllowOverride None
Require all granted
</Directory>
<Directory /var/www/>
Options Indexes FollowSymLinks
AllowOverride All
Require all granted
</Directory>
Also my .htaccess file is doing other jobs (i.e. redirecting the 404 to filenotfound.php ) without any problem. So why is this rewrite rule not working? How can I possibly debug the .htaccess file?

Answer 1

I still see my webpages with .php extension in my browser.
Well you don't even have a rule to redirect a request with .php to a URL without it.
Have your rules as this:
# 1 ---- Establish a custom 404 File not Found page ----
ErrorDocument 404 /filenotfound.php
# 2 ---- Prevent directory file listing in all of your folders ----
IndexIgnore *
RewriteEngine On
## hide .php extension
# To externally redirect /dir/file.php to /dir/file
RewriteCond %{THE_REQUEST} \s/+(.+?)\.php[\s?] [NC]
RewriteRule ^ /%1 [R=302,L,NE]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{DOCUMENT_ROOT}/$1\.php -f [NC]
RewriteRule ^(.+?)/?$ /$1.php [L]