redirect url ends with .php page to custom 404 page using htaccess caused the custom 404 page broke

Question

RewriteEngine On
ErrorDocument 404 /exception/404.php
//if url ends with .php/ , show custom 404 page
RewriteRule .php/$ - [R=404,L]
//this line caused the custom 404 page broken
RewriteRule .php$ - [R=404,L]

before I added line 4: speedcubing.top/index.php

(show the index page)

speedcubing.top/index.php/

(show custom 404 page)

after I added line 4: speedcubing.top/index.php speedcubing.top/index.php/

they both showing:

Not Found

The requested URL was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Answer 1

ErrorDocument directive and RewriteRule directive are from different Apache modules that run at different times. Hence setting R=404 doesn't cause Apache to invoke ErrorDocument handler and it ends up showing default 404 Apache handler.

You should add this line in your /exception/404.php to set a custom http response code:

<?php
http_response_code(404);
// rest of the code
?>

And have your .htaccess code like this:

ErrorDocument 404 /exception/404.php

RewriteEngine On

# if url ends with .php or .php/, show custom 404 page
RewriteCond %{REQUEST_URI} !^/exception/404\.php$ [NC]
RewriteRule \.php/?$ exception/404.php [NC,L]