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Troubleshooting Common WordPress Multisite Upgrade and Image Display Issues

33 threads Sep 7, 2025 Core → Networking wordpress

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Upgrading a WordPress Multisite network can sometimes lead to unexpected problems, leaving site administrators searching for solutions. Based on community reports, two of the most frequent issues are images failing to display after an upgrade and persistent upgrade network loops. This guide explains why these problems occur and provides steps to resolve them.

Problem 1: Images Not Displaying After Upgrade (Especially to 6.8)

Why This Happens: A known issue with WordPress 6.8 affected some older Multisite installations. The problem often manifests as empty image placeholders in the media library and on the front end, even though the image files are present on the server. Error messages may mention functions like wp_is_block_theme being called incorrectly.

Common Solutions:

  1. Check for a Patch: The WordPress core team is typically quick to address widespread bugs. Check the official WordPress development blog or the support forums to see if a point release (e.g., 6.8.1) has been issued to fix this specific problem. Upgrading to the latest version is often the simplest solution.
  2. Debug for Clues: Enable WordPress debugging by adding these lines to your wp-config.php file. This may reveal more specific error messages related to the image function calls. 
    define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true ); // Logs errors to wp-content/debug.log
define( 'WP_DEBUG_DISPLAY', false ); // Prevents errors from being printed on screen
  3. Review File Permissions: Ensure your file and directory permissions are correct (usually 644 for files, 755 for directories). Incorrect permissions can prevent WordPress from reading or generating image files correctly.

Problem 2: The Endless "Upgrade Network" Loop

Why This Happens: After a core update, you may be prompted to "Upgrade Network." This process updates the database for all sites in your network. However, the process can get stuck in a loop, repeatedly asking you to upgrade. This is frequently caused by server timeouts (504 Gateway errors) during the lengthy process of updating many subsites, or by inconsistencies in the database records for individual sites (e.g., mismatched siteurl or home values in the wp_[site_id]_options tables).

Common Solutions:

  1. Investigate Server Timeouts: A 504 error is a server-level issue. Contact your hosting provider and ask them to investigate timeout settings for PHP scripts and database connections. You can also request increased limits specifically for the upgrade process.
  2. Check Site URLs in the Database: Manually inspect the siteurl and home values for subsites in their respective wp_options tables (e.g., wp_2_options). Look for and correct common inconsistencies like mixing http:// and https://, or typos in the domain name.
  3. Run the Upgrade for a Single Site: You can often force the upgrade for a stubborn site by visiting its specific database upgrade URL directly: https://yoursite.com/subsite/wp-admin/upgrade.php.

General Multisite Upgrade Best Practices

  • Always Back Up First: Always create a complete backup of your files and database before starting any upgrade.
  • Deactivate Plugins: As seen in multiple threads, network-deactivating all plugins before upgrading can prevent many conflicts and fatal errors.
  • Update in a Staging Environment: If possible, test the entire upgrade process on a staging copy of your live site first. This allows you to identify and fix problems without affecting your users.

If you continue to experience issues, the WordPress support forums are an excellent resource for getting help from the wider community who may have encountered the same specific setup or error.

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