Troubleshooting Regenerate Thumbnails: Common Issues and Solutions

If you've found that the Regenerate Thumbnails plugin isn't working as expected, you're not alone. This is a common issue with a few well-known causes. This guide will walk you through the most frequent problems and how to resolve them.

Common Problem: Images Not Regenerating

Users often report that they run the tool, but their images do not update to the new sizes. This can be frustrating, especially after changing settings under Settings → Media.

Why This Happens

Several factors can prevent successful regeneration:

• Plugin Conflicts: Other plugins, particularly image optimization tools like Imagify, can sometimes interfere with the regeneration process.
• Cached Data: Old, cached versions of your images might be served by your browser or a caching plugin, making it appear as if the regeneration failed.
• Known Plugin Bug: A known issue related to the "Update the content of posts to use the new sizes" option existed in older versions of the plugin. This option was disabled in recent updates to prevent problems.
• File Name Inconsistencies: Having images with the same base name but different file extensions (e.g., 203-1.jpg vs. 203-1.jpeg) in your uploads folder can sometimes cause unexpected behavior.

How to Troubleshoot and Fix It

1. Update the Plugin

First, ensure you are using the latest version of Regenerate Thumbnails. The development team has addressed several known bugs in recent releases. An outdated version is a common source of problems.

2. Clear All Caches

Clearing your browser's cache and cookies is a good first step, but it's often not enough. You must also clear any server-side or plugin-based caches:

• Clear your WordPress caching plugin's cache (e.g., WP Rocket, W3 Total Cache).
• If you use a Content Delivery Network (CDN) like Cloudflare, purge its cache.
• Clear your server-level cache or object caching (e.g., Redis, Memcached) if applicable. Contact your web host for assistance with this.

3. Check for Plugin Conflicts

Temporarily deactivate all other plugins, especially image optimization and caching plugins. Then, try regenerating your thumbnails again. If it works, reactivate your plugins one by one to identify which one is causing the conflict.

4. Verify the Uploads Folder

Access your site's files via FTP or your hosting file manager. Navigate to /wp-content/uploads/ and locate the image files in question. Check if the newly regenerated image sizes have actually been created there. This will tell you if the issue is with generation or with display/caching.

5. Check File Names

As seen in one user's report, having two files with identical names but different extensions (e.g., .jpg and .jpeg) can lead to confusion. Ensure your image files have unique names to avoid any potential conflicts.

By methodically working through these steps, you can identify and resolve the issue preventing Regenerate Thumbnails from working correctly on your site.