Troubleshooting Common WordPress Multisite Issues: A Comprehensive Guide

WordPress Multisite is a powerful tool for managing multiple websites from a single installation. However, its complex nature can sometimes lead to confusing and frustrating problems that don't occur on standard WordPress sites. Based on common issues reported in the community, this guide will help you diagnose and resolve some of the most frequent Multisite headaches.

1. The Dreaded White Screen of Death

The Problem: You click to edit or create a page on a subsite and are met with a blank, white screen. No error message, just nothing.

Why It Happens: A blank white screen often indicates a PHP error that is being suppressed or not displayed. This can be caused by a plugin or theme conflict, incorrect file permissions, or a problem with the Multisite network configuration itself.

How to Fix It:

• Enable Debugging: The first step is to make errors visible. Edit your wp-config.php file and ensure these lines are present and set to true:

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

  This will often reveal the underlying PHP error directly on the screen, pointing you to the culprit.
• Check Network Setup: Verify that your .htaccess and wp-config.php files contain the correct Multisite rules as shown in your Network Settings > Network Setup area. A single misplaced character can break everything.
• Test for Conflicts: As a test, rename the mu-plugins directory (if it exists) and deactivate all network-enabled plugins. Reactivate them one by one to identify if one is causing the conflict.

2. User Management Confusion

The Problem: You can't find the "Delete" option for a user on a subsite, or you're unsure how to completely remove a user from the entire network.

Why It Happens: Multisite handles users differently. A user account is global to the network but is only assigned to individual sites. The standard "Delete" option on a subsite's Users page merely removes them from that specific site, not the network.

How to Fix It:

• To remove a user from a single site, go to the subsite's Users page and select "Remove" from the bulk actions dropdown.
• To permanently delete a user from the entire network, you must go to the Network Admin dashboard (My Sites > Network Admin > Users). Here you will find the full delete option. Be cautious, as this will erase the user's account and can reassign their content.

3. Plugin and Theme Management Problems

The Problem: You are unable to install, delete, or manage network-activated plugins from the Network Admin dashboard.

Why It Happens: This is almost always caused by a plugin or theme conflict. Even if you haven't installed anything new, an update to an existing plugin can introduce a bug that breaks core functionality.

How to Fix It:

• Conflict Test: Deactivate all plugins simultaneously. If the issue is resolved, reactivate them one by one, checking the Network Admin after each activation to identify the problematic plugin.
• Check File Integrity: If deactivating plugins doesn't work, there may be a corrupt core file. Many hosting panels offer a "WordPress Repair" tool. Alternatively, manually re-upload the wp-admin and wp-includes folders from a fresh download of WordPress.

4. Disappearing or Corrupted Admin Elements

The Problem: Page attributes (like parent pages), category lists, or featured images won't load in the post editor, showing only a spinning icon or corrupted text (e.g., "Add for CTR").

Why It Happens: These elements often rely on AJAX requests to function. A conflict can break these requests. Corrupted text like "Add for CTR" strongly indicates that a plugin or theme is incorrectly modifying the HTML output of the admin screen.

How to Fix It:

• Clear Browser Cache & Cookies: A simple browser cache clear or logging out and back into WordPress can surprisingly fix many AJAX-related admin issues.
• Thorough Conflict Test: Switch a affected subsite to a default theme (Twenty Twenty-One) and deactivate all plugins, including network-activated ones. If the problem is resolved, restore your theme and plugins one by one to find the source of the conflict.

5. Critical Errors on a Single Subsite

The Problem: One specific subsite crashes with a "There has been a critical error on this website" message, while the rest of the network functions normally.

Why It Happens: The error is isolated to one site, which typically rules out network-wide core files or configuration. The cause is almost always a site-specific theme or plugin that has a fatal error.

How to Fix It:

• Enable Error Logging: The fastest way to diagnose this is to check your server's error log. This log is accessible through your hosting provider's control panel (e.g., cPanel). The log will contain the precise PHP error that is causing the crash.
• Access Recovery Mode: WordPress often enters Recovery Mode after a critical error, providing a link to log in and deactivate the offending plugin or theme. Check your email for a message from your website with this link.
• If you cannot log in, use your hosting file manager or FTP to manually rename the theme or plugins folder for that specific subsite to force WordPress to disable them.

By methodically working through these troubleshooting steps—enabling debugging, checking error logs, and performing conflict tests—you can resolve the vast majority of issues that arise in a WordPress Multisite network. Remember, the key is to isolate the problem by testing with default themes and deactivated plugins.