WordPress multisite .htaccess: subdomains vs subdirectories.

Why the two network types need different rules

In a subdomain network, WordPress identifies a site primarily from the hostname: for example, shop.example.com. In a subdirectory network, the site name is part of the path: for example, example.com/shop/. Apache must leave that first path segment available to WordPress in the subdirectory case.

The two network blocks, in full

Both go in the network root's .htaccess, between WordPress's own markers. Take the one that matches how your network identifies a site, whole — the lines are not interchangeable between the two.

# BEGIN WordPress
RewriteEngine On
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index\.php$ - [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]
# END WordPress

# BEGIN WordPress
RewriteEngine On
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]
# END WordPress

Neither block is wrapped in <IfModule mod_rewrite.c>, unlike the single-site block — that is how WordPress's own Network Setup screen writes them. The practical consequence is worth knowing: on a server without mod_rewrite these rules produce an outright error rather than quietly serving every subsite as the main site.

Three rules differ, and they account for the entire difference between the two topologies:

Copying a subdirectory rule into a subdomain network, or the reverse, is what produces the classic symptom: the main site works, and every subsite returns the main site's home page or a 404.

Use the Network Setup output as the source of truth

WordPress generates a configuration snippet when you create a network. That output reflects the network type and installation path that Core knows about, so it should take priority over copied snippets from a different host or topology. A network that was moved into a subdirectory or changed from subdirectories to subdomains deserves a full configuration review, not a one-line rewrite edit.