Force a 404 error when ".php" is present in URL - regex

Question

I have this .htaccess code which hides the .php extension. It works wonders.
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.+)$ $1.php
I'm now attempting to produce a 404 Not Found error when .php is present in the URL, because I want to force people to use URLs without .php. Here's the code I have now:
RewriteCond %{ENV:REDIRECT_STATUS} ^$
RewriteRule ^$ /home.php [QSA,L]
RewriteRule ^(.+)\.php - [L,R=404]
I am a complete newbie to .htaccess but the code above is causing a 404 error whenever I go to a .php page, even if .php is not in the URL.
What adjustments must I make in order to make it only cause a 404 Not Found when .php is in the URL?

Answer 1

Rewrite conditions only apply to the immediately following rule, which means:
RewriteCond %{ENV:REDIRECT_STATUS} ^$
only gets applied to
RewriteRule ^$ /home.php [QSA,L]
but not the rule that follows that:
RewriteRule ^(.+)\.php - [L,R=404]
The problem with this last rule is that it checks if the URI has a .php in it, which it will because you're adding the .php extension in your first rule:
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.+)$ $1.php
So you need to add another condition to prevent that from happening:
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.+)$ $1.php
RewriteCond %{ENV:REDIRECT_STATUS} ^$
RewriteRule ^$ /home.php [QSA,L]
RewriteCond %{THE_REQUEST} \ /+[^\?\ ]+\.php
RewriteRule ^ - [L,R=404]