I created a Rule in my HTACCESS file, to hide a sub-folder.

RewriteEngine On

RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s/?([^/]+)/([^/]+)/([^.]+)\.php [NC]
RewriteRule ^ /%1/%3 [R=301,L]

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^/]+)/([^/]+)/?$ $1/Project/$2.php [NC,L]

The first rule removes all file-extensions : php

The second rule will hide the folder "Project" from the URL

Both these rules are working perfectly.

However, when I tried to add a third rule, to hide another folder, it failed.

This second folder (Rolan) is in the same location as the "Project" folder, so I assumed that it should work simply by copy-pasting the second rule, and then adding a PREFIX to the beginning of the third rule :

RewriteEngine On
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s/?([^/]+)/([^/]+)/([^.]+)\.php [NC]
RewriteRule ^ /%1/%3 [R=301,L]

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^/]+)/([^/]+)/?$ $1/Project/$2.php 

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^gagoo/([^/]+)/([^/]+)/?$ $1/Rolan/$2.php [NC,L]

I added the prefix "gagoo" to the third rule.

Also, I removed the [NC,L] from the end of the second rule, and placed it at the end of the third rule.

Then, in my PHP code, I wrote the URL as follows : www.example.com/gagoo/Rolan/file_name

Both the first and second rules are still working. But, for the third rule, I am getting a "FILE NOT FOUND : 404" error.

The thing is : I wrote a JavaScript code, which opens "file_name" in a "New Window". (Still, I doubt that this could be the reason for the problem)

# -FrontPage-

RewriteEngine On
RewriteBase /
#RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]p

# BEGIN WordPress

# END WordPress

The .htaccess has the following.

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

#END WordPress