Complete Guide to Fixing WordPress Admin 404 Errors

If you can log into your WordPress admin dashboard but clicking any menu item returns a 404 error, the issue is typically caused by a plugin conflict or a server configuration problem. This guide provides a complete troubleshooting and resolution process.

Case 1: Admin 404 Caused by Plugin Conflict

This is the most common cause. An outdated, buggy, or incompatible plugin can break the admin routing.

Solution: Deactivate Plugins via Renaming

This method temporarily disables all plugins to confirm the source.

1. Connect to your server via SSH or FTP and navigate to the wp-content folder in your site's root directory.
2. Find the plugins folder and rename it to something else (e.g., plugins_deactivated).
3. Log back into your WordPress admin. All plugins are now disabled, and the admin pages should load normally.
4. Via SSH/FTP, rename the folder back to plugins.
5. Go to the Plugins page in your admin. All plugins will be inactive. Reactivate them one by one, testing the admin after each. The plugin that causes the 404 error to return is the culprit. Update or remove it.

Tip: Before starting, enable WordPress debug mode for more detailed error logs. Edit your wp-config.php file and change define('WP_DEBUG', false); to define('WP_DEBUG', true);. For shared hosting users, download the file via FTP, edit it locally, and re-upload it.

Case 2: Nginx Server Configuration Issue

If your WordPress runs on Nginx, a 404 error in the admin area is often due to incomplete URL rewrite rules, preventing correct routing for URLs like /wp-admin (missing the trailing slash).

Solution 1: Edit the Nginx Site Configuration

This is the recommended fix. Edit your Nginx site configuration file (e.g., /etc/nginx/sites-available/your-site). Ensure the following rules are present within the main location / block handling WordPress:

location / {
    try_files $uri $uri/ /index.php?$args;
}

# Specific rule for wp-admin
rewrite /wp-admin$ $scheme://$host$uri/ permanent;

After adding the rules, test the configuration with sudo nginx -t. If successful, reload Nginx with sudo systemctl reload nginx.

Solution 2: Use an Existing WordPress Configuration Snippet

If you use an environment like an LNMP one-click install, your config may include a line like include wordpress.conf;. Check the wordpress.conf file to ensure it contains the rewrite rules above. Add them if missing.

Warning: Some outdated tutorials incorrectly suggest adding an HTML <base> tag to wp-config.php. This is wrong and ineffective, as that file is a PHP script. Always use the correct server configuration method.

Summary and Prevention

When facing an admin 404, first try deactivating all plugins. If the problem persists, check your server rewrite rules. The best practice to avoid such issues is to regularly update WordPress core, themes, and plugins, and always back up your site before updates.