WordPress Multisite cookie error (and how to fix It)

How to fix the cookies error in a WordPress Multisite management setup

1. Adjust browser settings

Start by ensuring that browser settings allow the use of cookies. Provide users with clear instructions on adjusting these settings in popular browsers such as Chrome, Firefox, and Safari.

Chrome browser settings

1. Open Chrome settings.
2. Navigate to Privacy and Security.
3. Adjust cookie settings to allow cookies.

Firefox browser settings

1. Open Firefox settings.
2. Go to the Privacy & Security section.
3. Configure cookie settings to enable them.

Safari browser settings

1. Access Safari preferences.
2. Navigate to the Privacy tab.
3. Allow cookies from websites you visit.

2. Check plugin and theme compatibility

Perform a thorough check of plugins and themes installed on your WordPress Multisite network. Identify any conflicting elements and take corrective action.

Disable plugins one by one and check if the cookies error persists. Revert to a default WordPress theme (for example, Twenty Twenty-One) to see if the issue is related to the current theme.

3. Review and configure the network-wide cookie settings

Within the WordPress Multisite settings, review and configure the network-wide cookie settings. Make sure they work with the particular requirements of your websites and are not contributing to the cookies error.

1. Access the WordPress Dashboard.
2. Navigate to Network Admin > Settings > Network Settings.
3. Review the Cookie Settings section and adjust as needed.

When dealing with a cookies error in a WordPress Multisite setup, you might find that adjusting certain configurations or using the WordPress Command Line Interface (WP-CLI) commands can be helpful. Below are some recommendations.

3a. Edit the wp-config.php file

Adjusting configurations in the wp-config.php file can be a solution. Here are some settings you might consider adding to address cookies issues:

define('COOKIE_DOMAIN', '');
define('COOKIEPATH', '');
define('SITECOOKIEPATH', '');
define('ADMIN_COOKIE_PATH', '/');
define('COOKIEHASH', md5('your-unique-string-here'));

Ensure you replace your-unique-string-here with a unique string.

3b. Use WP-CLI commands to manage the network

You can use the WP-CLI tool to perform various tasks related to your WordPress Multisite network. Here are some relevant commands in the next section.

→ Update network settings

Update the network settings using the following commands:

wp site option update siteurl 'https://your-multisite-url.com'
wp site option update home 'https://your-multisite-url.com'

Replace https://your-multisite-url.com with your actual WordPress Multisite URL.

→ Search and replace the URL

If your WordPress Multisite URL has changed, you might need to update it in the database. WP-CLI can help with that:

wp search-replace 'http://old-url.com' 'https://new-url.com' --network

Replace http://old-url.com with your old URL and https://new-url.com with your new URL. Remember to replace the placeholder URLs used above with actual values.

→ Update cookie settings

You can use the wp config edit command to edit the wp-config.php file directly:

wp config edit --raw

This command opens the wp-config.php file in the default text editor. You can manually add or modify the cookie-related constants.

3c. Clearing cookies via WP-CLI

In some cases, it might be necessary to clear cookies. You can use browser tools for this, but if you want to automate it, you can use a script:

wp db query "DELETE FROM wp_options WHERE option_name LIKE '%_settings_%'"
wp cache flush

This script clears settings that might be related to cookies. Please be aware that the wp cache flush command addresses the object cache. If your site employs Redis object caching and it is enabled, this command will clear the Redis cache. However, if your site uses a different caching mechanism (for example, or Memcached or server-level caching), additional steps specific to that system may be required.

3d. Check web server configuration

Make sure that your web server has been configured properly for handling cookies. Verify that PHP sessions are enabled, and the server has enough resources to handle the demands of a WordPress Multisite network:

php -i | grep session

Check for any session-related configurations that might be impacting cookie functionality.

3e. Debug with WP_DEBUG

Enable WP_DEBUG in your wp-config.php file to log any potential errors or warnings that might be related to the cookies issue.

define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);

This debug mode can help you identify any underlying problems and streamline the troubleshooting process.

4. Inspect and troubleshoot cookies with browser developer tools

Leverage developer tools to directly from your browser. These advance tools can provide valuable insights into how cookies are being set and whether any conflicts exist:

• Chrome: Press Ctrl + Shift + I (Windows/Linux) or Cmd + Opt + I (Mac) to open Chrome DevTools. Navigate to the Application tab and explore the Cookies section.
• Firefox: Press Ctrl + Shift + I (Windows/Linux) or Cmd + Opt + I (Mac) to open Firefox Developer Tools. Navigate to the Storage tab and explore the Cookies section.

5. WordPress Multisite domain mapping

If you are using domain mapping in your WordPress Multisite, ensure that the domain mapping configurations are accurate. Incorrect settings can lead to cookies errors:

define('COOKIE_DOMAIN', '');

Verify that the COOKIE_DOMAIN setting in your wp-config.php is appropriately configured for your domain mapping.

6. Update WordPress and plugins

Ensure that you are using the latest version of WordPress. All plugins and themes should be on the newest version. Often releases are available that revise functionality to address compatibility issues, including those related to cookies:

wp core update
wp plugin update --all

7. Audit security plugins

If you have security plugins installed, they might interfere with cookie functionality. Check the settings of security plugins and temporarily deactivate them for testing purposes.

8. Monitor user roles and permissions

WordPress user roles and file permissions can sometimes be affected by cookies issues. Confirm that user roles are correctly assigned and file permissions are set up accurately within your multisite network.

9. Perform database optimization

Perform a database optimization to ensure that your WordPress Multisite database is running efficiently. Use plugins like WP-Optimize or WP-Sweep to clean up unnecessary data, which may contribute to unexpected cookie behavior:

wp db optimize

10. Evaluate caching strategies

Evaluate your caching strategy. Caching plugins or server-level caching mechanisms can sometimes interfere with cookies. Clearing the cache or adjusting caching settings might help in resolving persistent cookies errors:

wp cache flush

Please note that the wp cache flush command primarily addresses the object cache. For Nexcess WordPress sites, the object cache is typically managed by Redis.

11. Look at the Content Delivery Network (CDN) settings

If you are using a CDN, ensure that it is configured correctly for your multisite network. Improper CDN settings can lead to cookie-related issues. Check CDN documentation for multisite compatibility guidelines.

12. Consider potential Cross-Origin Resource Sharing (CORS) errors

Cross-Origin Resource Sharing (CORS) request blocked issues can impact cookie functionality, especially in multisite setups with multiple domains. Make sure that your web server is configured to handle CORS correctly.

13. SSL and HTTPS setup

Confirm that your WordPress Multisite is using SSL and serving pages over HTTPS. Insecure connections can lead to cookie-related problems, especially if you are dealing with authentication cookies.