To activate Multisite on a self-hosted WordPress installation, first back up the database and files, then add define( 'WP_ALLOW_MULTISITE', true ); to wp-config.php above the /* That's all, stop editing! */ comment. After refreshing the dashboard, open Tools > Network Setup, choose subdomains or subdirectories, enter the network title and administrator email, and apply the generated code to wp-config.php and .htaccess. Log in again to finish.
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The first constant only unlocks the setup screen; it does not complete the network. WordPress creates the remaining network configuration after you submit the Network Setup form. Follow the sequence below to avoid losing access to the existing site.
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What activating Multisite changes
WordPress Multisite turns one WordPress installation into a network that can contain multiple sites. The files and core installation remain shared, while the network is managed from a central administration layer. Your current single site becomes the first site in that network; creating the network updates that existing site rather than making a disposable test copy.
Activation is therefore a configuration change, not a plugin installation. It edits the installation’s configuration and rewrite rules, and the URL model you select affects how every additional site will be reached. Treat the process like a server migration: make a recoverable backup, remove variables such as active plugins, and keep your hosting control-panel access available.
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Prepare the installation before opening Network Setup
Back up both database and files
Make a complete backup immediately before starting. The database contains posts, pages, settings, users, and site records; the files backup must include wp-config.php, the WordPress files, themes, plugins, and uploads. Store the backup somewhere outside the server so a damaged configuration or failed restore does not leave you without a recovery copy.
- Confirm that the database backup can actually be downloaded or restored, rather than merely showing a “completed” message.
- Save the current
wp-config.phpand.htaccessfiles separately. You will edit both. - Record the current site URL and administrator login so you can test the original site after the network is enabled.
Confirm that pretty permalinks work
On the single site, open a few front-end URLs that are not the home page, such as a post or page using the site’s normal permalink format. Pretty permalinks need to be functioning before the network is created because Multisite relies on rewrite rules to route requests to the correct site. If these URLs already return 404 errors, fix the single site first and postpone network creation.
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Deactivate every plugin
Deactivate all plugins before running Network Setup. A plugin can alter rewrite rules, login behavior, or database settings while WordPress is adding network configuration. Deactivation is temporary: after the network exists, you can reactivate plugins in a controlled order and identify any that are incompatible with a network environment.
Check hosting constraints
Multisite is configured inside WordPress, but the web server and DNS still determine whether the chosen URLs resolve. Subdomain networks commonly require a wildcard DNS record so arbitrary subdomains reach the WordPress installation; whether that is available depends on your DNS provider and host. On Nginx or managed one-click installations, the generated Apache-style .htaccess rules may not be used, and the host may require a different rewrite configuration or may restrict Multisite. Check the host’s own documentation before changing production settings.
Choose subdomains or subdirectories
Network Setup asks how new sites should be addressed. This choice is fundamental: WordPress writes different rewrite and URL behavior for each model, and changing models later is a migration rather than a simple toggle.
| URL model | Example for a main site at example.com |
Infrastructure implication | Best fit |
|---|---|---|---|
| Subdomains | game1.example.com |
Each site receives its own host name. A wildcard DNS record is commonly needed so new subdomains resolve to the WordPress server; DNS support is host-dependent. | Networks that want clearly separated site addresses or expect many independent properties. |
| Subdirectories | example.com/game1/ |
Sites live below the main domain path and rely on the installation’s rewrite rules. No separate host name is used for each site. | Networks that prefer one domain and a path-based structure. |
For an existing site, the setup screen may present URL choices based on the installation’s current address and age. Read the generated instructions carefully instead of assuming both models are available in every situation. If your planned structure depends on DNS changes, complete those with your host before inviting users to the new sites.
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1. Open the configuration file safely
Locate the wp-config.php file in the root of the WordPress installation. Use your host’s file manager, SFTP, or another method that preserves the file as plain text. Download a copy before editing it, and do not paste the PHP line inside another directive, a function, or an HTML block.
2. Add the WP_ALLOW_MULTISITE constant
Insert this exact line above the existing stop-editing comment:
define( 'WP_ALLOW_MULTISITE', true );The relevant area should look similar to this, although the surrounding settings will differ on your site:
define( 'WP_ALLOW_MULTISITE', true );
/* That's all, stop editing! Happy publishing. */Use the comment’s actual wording and location in your file as the placement reference. The important rule is that the constant appears before the stop-editing comment and remains inside the PHP file. Do not add MULTISITE manually at this stage. WP_ALLOW_MULTISITE unlocks the menu; the network-level MULTISITE setting is supplied later in the generated snippet.
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3. Refresh the WordPress dashboard
Save the file, return to the WordPress dashboard, and refresh the page. A new Network Setup item should appear under Tools. If it does not, check that the edited file belongs to the installation serving the dashboard, that the line is above the stop-editing comment, and that the PHP syntax is intact.
4. Open Tools > Network Setup
Select Tools > Network Setup. This screen is the network creation wizard. It does not merely turn on a hidden flag; it collects the values WordPress needs and then prints the exact configuration fragments for your installation.
5. Enter the network identity
Provide a network title and the network administrator’s email address. Use an email address that the administrator can access because it identifies the person responsible for network-level notices. The title is an administrative label for the network, so choose wording that will still be clear if you later host several game sites, projects, or teams on it.
6. Select the URL structure
Choose Sub-domains or Sub-directories according to the decision above. Read the explanatory text on the screen, especially if WordPress limits one option for the current installation. The selection determines the addresses shown for new sites and the rewrite code WordPress generates.
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Submit the Network Setup form. WordPress displays code for two files:
- A new block for
wp-config.php, which contains the network constants and the values generated for your site. - A rewrite block for
.htaccess, which routes requests for the network’s sites when Apache-style rewrites are in use.
Copy each block exactly as displayed. Do not substitute a snippet from another installation, change quotation marks, or combine the two blocks. The generated values reflect your domain, path, and selected URL model.
8. Paste the generated wp-config.php block
Return to wp-config.php and paste the generated block where the Network Setup instructions specify. Keep the original WP_ALLOW_MULTISITE line unless WordPress’s instructions clearly show a replacement location; the setup output is the authoritative source for the final arrangement. Preserve the PHP opening and closing structure and keep all constants inside the PHP file.
9. Paste the generated .htaccess rules
Open the installation’s .htaccess file and replace or update the existing WordPress rewrite section with the block generated by Network Setup, following the on-screen instructions. Keep unrelated server directives that your host requires. If no .htaccess file exists, or your server uses Nginx, stop and ask the host how to translate the generated Apache rules; pasting them into an unused file will not configure Nginx.
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10. Log in again and confirm network mode
Save both files, then return to the dashboard. WordPress normally asks you to log in again. Complete that login. You should be returned to the Network Setup area as the network administrator, and the administration interface should expose network-level controls in addition to the original site’s controls.
Verify the finished network
Do not assume success merely because the dashboard reloads. Run a short, reversible test before reactivating plugins or announcing the network.
- Open the original site’s home page and at least one deep permalink in a private browser window.
- Confirm that the administrator can log in and reach the network administration area after the forced re-login.
- Create a test site using the URL model you selected, if your role and hosting plan permit it.
- Visit the test site’s front end and dashboard. Check that its address follows the expected subdomain or subdirectory pattern.
- Review the browser and server error logs for PHP syntax errors, redirect loops, or rewrite failures before restoring normal traffic.
After these checks, reactivate plugins one at a time or in small, documented groups. If a failure appears, deactivate the last group and retest; this makes the incompatible plugin identifiable instead of leaving several simultaneous causes.
What the generated code means
The first constant and the network constants are different
WP_ALLOW_MULTISITE is an invitation to show the setup tool. It does not, by itself, make WordPress serve multiple sites. The second block, generated after you submit Network Setup, contains the network-level settings that tell WordPress it is operating as a Multisite installation. Adding only the first line and stopping there leaves the installation in an unfinished state.
Why both files receive instructions
wp-config.php loads before WordPress initializes, so it is the appropriate place for network constants and database-related configuration. The rewrite file handles incoming URLs before WordPress chooses a site. Both pieces are required for a normal Apache-style setup: the PHP constants define the network, while the rewrite rules direct requests to it.
Troubleshooting common activation failures
“Network Setup” is missing from Tools
- Reopen the exact
wp-config.phpused by the live installation. - Confirm the line is spelled exactly
define( 'WP_ALLOW_MULTISITE', true );. - Move it above the
/* That's all, stop editing! */comment if it is below that point. - Check for a missing semicolon, curly quotation marks, or text placed outside PHP tags.
- Save the file, sign out, and refresh the dashboard again.
The site shows a PHP error or a blank page after editing
Restore the saved copy of wp-config.php immediately to bring the original site back, then compare the edited file character by character. A malformed constant or pasted block can prevent PHP from loading anything. Once the single site works again, repeat the edit with a plain-text editor and paste only the exact generated code.
Permalinks or site pages return 404 errors
First test the original site’s permalinks, then inspect whether the generated rewrite block was pasted into the correct .htaccess file. Keep the block in the installation directory specified by WordPress. On a server that does not use Apache-style rewrites, the host must provide the equivalent configuration; an .htaccess edit alone cannot change Nginx routing.
Subdomain sites do not resolve
Check DNS and the host’s virtual-host configuration. A subdomain network commonly needs a wildcard record that sends otherwise-unlisted subdomains to the WordPress server. DNS propagation and wildcard support vary by provider, so this is an infrastructure issue rather than a missing WordPress checkbox. Until DNS is correct, the network may work in the dashboard while public subdomain URLs fail.
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Return to the plugin screen, deactivate the most recently enabled plugin or group, and retest both the main site and a second site. Continue in small batches. Because all sites share the installation, a plugin that changes global rewrites, login handling, or database behavior can affect more than the site where it was activated.
The host’s installer does not offer Multisite
Do not infer that the absence of a one-click option means the WordPress software cannot be configured. Some managed installers and hosting environments impose their own restrictions, however. Ask the host whether it supports a self-hosted Multisite network, wildcard subdomains, and the required rewrite configuration before attempting production changes.
Operational checklist after activation
- Keep the pre-activation database and file backups until the network has passed real-world testing.
- Document whether the network uses subdomains or subdirectories and where DNS and rewrite rules are managed.
- Record the network title and administrator email used during setup.
- Keep a copy of the final
wp-config.phpand.htaccessfiles in your change log. - Reactivate plugins deliberately, testing the main site and at least one additional site after each batch.
- When adding a site, verify its URL, front end, dashboard, media upload, and permalink behavior before handing it to users.
- Repeat backups before future network-level configuration changes.
When to postpone Multisite
Wait if you cannot make a verified backup, cannot edit the required files, or do not control the DNS and server settings required by your selected URL model. Also postpone if the existing single site already has broken pretty permalinks or unexplained PHP errors. Multisite adds a network layer to that installation; it does not repair underlying hosting or application problems.
For a stable self-hosted installation with working permalinks, file access, and a host that supports the chosen URL structure, the process is deterministic: unlock the tool with WP_ALLOW_MULTISITE, let Network Setup generate the site-specific snippets, apply both snippets, and verify before restoring plugins.
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