Converting a Standard WordPress Site to a Multisite Network

A standard single-site WordPress installation can be converted into a Multisite network directly on the server without reinstalling WordPress. The conversion can be configured using either a subdirectory or a subdomain structure.

At Seravo, Multisite support is included in our WP Corporate and WP Enterprise hosting plans. Before you begin, please ensure that your current plan supports Multisite.

Preparations Before the Conversion

Before modifying your database or configuration files, complete the following preparations:

Create a Fresh Backup:
Create a manual backup point before making any changes:
```
wp-backup
```
Review Alias Domains and Redirects:
In a standard WordPress installation, any additional domain pointing to the site resolves to the front page by default. In a Multisite network, any incoming domain not explicitly mapped to a subsite will redirect to the registration page (wp-signup.php).
- If you have alias domains that should redirect to your primary domain, set up server-level redirects in nginx within /data/wordpress/nginx/redirects.conf.
- Do not rely on the Redirection plugin, as its behavior in a Multisite environment is not reliable.
Temporarily Disable Caching and Security Plugins:
If your site uses heavier caching, firewall, or security plugins, we recommend disabling them temporarily during the conversion to avoid conflicts.

Creating a Subdirectory-Based Multisite

In a subdirectory structure, new subsites will reside at paths formatted as example.com/subsite/.

Connect to your site via SSH.
Run the conversion command using WP-CLI:
```
wp core multisite-convert
```

Enable Seravo's Multisite routing rules for the Nginx web server:

wget https://seravo.com/network.conf-example -O /data/wordpress/nginx/network.conf
wp-restart-nginx

Add the cookie domain configuration to wp-config.php to prevent login issues:
```
nano /data/wordpress/htdocs/wp-config.php
```
Locate the Multisite definitions and add the following line:
```
define( 'COOKIE_DOMAIN', $_SERVER['HTTP_HOST'] ?? '' );
```
Update your permalink structure:
Navigate to Settings > Permalinks in the WordPress dashboard to review your structure, or flush your rewrite rules via the terminal:
```
wp rewrite flush
```

Creating a Subdomain-Based Multisite

In a subdomain structure, new subsites operate under their own subdomains formatted as subsite.example.com.

Connect to your site via SSH.
Run the conversion command with the --subdomains flag:
```
wp core multisite-convert --subdomains
```

Enable Seravo's Multisite routing rules for the nginx web server:

wget https://seravo.com/network.conf-example -O /data/wordpress/nginx/network.conf
wp-restart-nginx

Add the cookie domain configuration to wp-config.php:
```
nano /data/wordpress/htdocs/wp-config.php
```
Add the following line alongside the Multisite definitions:
```
define( 'COOKIE_DOMAIN', $_SERVER['HTTP_HOST'] ?? '' );
```
Wildcard SSL Certificate and DNS:
To ensure that upcoming subdomains work without browser SSL warnings, contact Seravo Customer Support to activate a wildcard SSL certificate for your primary domain, and verify that a wildcard * DNS record points to Seravo.

Verifying the Conversion

Once you have executed the commands and saved your configurations:

Check your network status using Seravo's dedicated CLI tool:
```
wp-network-status
```
The command should display essential network details, the active structure type, and all sites in the network.
Flush the site cache:
```
wp-purge-cache
```
Log in to the WordPress dashboard. A new menu item, My Sites > Network Admin, should now appear in the top toolbar.

Troubleshooting and Exceptions

Login Fails ("Cookies are blocked"):
This is caused by a missing cookie domain configuration. Verify that define( 'COOKIE_DOMAIN', $_SERVER['HTTP_HOST'] ?? '' ); is present in /data/wordpress/htdocs/wp-config.php above the /* That's all, stop editing! */ line.
Subsites Return 404 Not Found Errors:
The nginx routing configuration is missing or was not reloaded. Verify that /data/wordpress/nginx/network.conf exists and run wp-restart-nginx.
The /blog/ Prefix Appears in Post URLs (Subdirectory Networks):
WordPress automatically prepends /blog/ to post URLs on the primary site in subdirectory networks to prevent URL collisions with new subsites. You can remove this prefix in the Network Admin: Network Admin > All Sites > Dashboard of Primary Site > Settings > Permalink Structure.