Fixing custom 404 pages broken by Wordpress in a subdirectory

Question

I used Installatron to install Wordpress in a subdirectory of an existing PHP website, to add a blog to that website. My main website is administered via cPanel.

Here's my website directory structure:

/-- public_html
    /-- .htaccess
    /-- index.php
    /-- about.php
    /-- etc.
    /-- product-pages
        /-- index.php
        /-- product-a.php
        /-- product-b.php
        /-- etc.
    /-- blog
        /-- wp-admin
        /-- wp-content
        /-- wp-includes
        /-- .htaccess
        /-- .user.ini
        /-- index.php
        /-- etc.

The Wordpress installation added the standard Wordpress section to the root .htaccess:

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

# END WordPress

As many people have found, this disables my custom 404 error pages for the main website, displaying the site homepage instead. 404 errors for the Wordpress blog work as expected and display the Wordpress custom 404 error.

Wordpress also created a .htaccess in its own /blog installation directory. It includes this section:

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

# END WordPress

I found that by removing the Wordpress section from the .htaccess in the main website root, both main website custom 404 and Wordpress custom 404 functionality appear to work correctly. Is there any reason why I shouldn't do this?

Is the addition of a Wordpress section to the root .htaccess by the Installatron Wordpress installer incorrect behaviour for a subdirectory installation?

Answer 1

I found that by removing the Wordpress section from the .htaccess in the main website root, both main website custom 404 and Wordpress custom 404 functionality appear to work correctly. Is there any reason why I shouldn't do this?

Yes, this is what I was going to suggest.

If WordPress is installed in the subdirectory /blog and is accessed by the URL /blog/ then there is no need for the WordPress .htaccess file in the document root. You certainly shouldn't have both.

However, the "WordPress" .htaccess file in the document root would seem to be rewriting to /index.php in the document root, which is incorrect anyway?!

Is the addition of a WordPress section to the root .htaccess by the Installatron Wordpress installer incorrect behaviour for a subdirectory installation?

Well, you would need an .htaccess file in the root if you installed WordPress in the /blog subdirectory, but the /blog subdirectory was hidden from the URL-path. (It would, however, be written differently to the current .htaccess file in root. In fact, it would be the same as the .htaccess file currently in the /blog subdirectory.)