WebP is a modern image format developed by Google that provides superior compression for images on the web, allowing websites to load faster while maintaining high quality visuals. WordPress, being the most popular content management system, has adopted support for WebP images as of version 5.8. However, despite its advantages, users often encounter issues with WebP image thumbnails going blank in the WordPress media library or on the front end of their websites. This can be both confusing and frustrating, especially when managing large amounts of visual content.

Understanding the Problem: WebP Thumbnails Going Blank

When thumbnails for WebP images appear blank in the WordPress media library or on the site, it usually points to a compatibility or configuration issue. Typically, users might notice:

• Thumbnails appear as blank white or gray boxes
• Media library shows broken links or no preview at all
• The front end displays placeholders instead of actual images

The causes behind these symptoms can range from server-side limitations to theme or plugin conflicts. Troubleshooting these issues involves examining the server configuration, WordPress settings, and file compatibility.

Common Causes of WebP Thumbnail Issues

There are several reasons why WebP thumbnails may appear blank in WordPress:

1. Server Library Limitations

WordPress relies on server-side libraries like GD or Imagick to process images. For WebP support, these libraries must be compiled with WebP capabilities. If your server lacks this support, WordPress may upload the image successfully but fail to generate thumbnails.

To check this, create a PHP info file or reach out to your hosting provider to confirm if GD or Imagick supports WebP. If not, updating PHP or recompiling these libraries might be necessary.

2. File Permissions and Ownership

Incorrect file permissions can prevent WordPress from generating thumbnails even for supported image formats like WebP. Verify the following:

• Uploads directory has 755 or 775 permissions
• Individual image files have 644 permissions
• Ownership of files and directories matches the web server user

Using an FTP client or your hosting control panel, adjust permissions and ownership accordingly.

3. Theme or Plugin Conflicts

Some WordPress themes or plugins may override default media handling functions, which can interfere with the generation and display of WebP thumbnails. A faulty plugin might rewrite the <img> tag or enqueue a script that blocks WebP rendering in certain browsers.

To identify the culprit:

• Disable all plugins and switch to a default theme like Twenty Twenty-Three
• Upload a new WebP image and check if thumbnails generate correctly
• Re-enable plugins one by one to isolate the conflict

4. Browser Compatibility Issues

Although modern browsers widely support WebP, older versions of Safari or Internet Explorer may not. In the WordPress dashboard, if you’re using a browser without full WebP support, thumbnails may appear blank. Try switching to a recent version of Chrome, Firefox, or Edge to see if the issue persists.

5. Incomplete or Corrupted WebP Files

Sometimes, uploaded WebP files may be incomplete or improperly encoded, causing WordPress to fail in processing them. To test this, open the image in a local image viewer or reconvert the image using tools like:

• Squoosh
• CloudConvert
• cwebp command-line tool

Once you have a valid and working WebP image, try uploading it again to see if thumbnails are generated successfully.

Recommended Fixes for Blank WebP Thumbnails

If you’ve determined why thumbnails are blank, follow these suggested solutions:

1. Install or Upgrade GD/Imagick with WebP Support

Ask your hosting provider to enable or upgrade WebP support in the GD or Imagick PHP libraries. On many modern shared hosting environments, GD with WebP support is already enabled. If you manage your own server, you can recompile PHP with the necessary flags or install a newer version.

2. Use Plugins That Support WebP

Plugins like ShortPixel, Smush Pro, or EWWW Image Optimizer handle WebP conversions and screen compatibility much better than the native WordPress uploader. Some of these plugins offer fallback images for unsupported browsers as well.

If you’re using a caching or CDN plugin (like WP Rocket or Cloudflare), make sure it’s configured to handle WebP images properly.

3. Regenerate Thumbnails

If you’ve fixed the root cause but existing images still have blank thumbnails, use the Regenerate Thumbnails plugin to recreate them.

• Install and activate the plugin from the WordPress repository
• Navigate to Tools → Regenerate Thumbnails
• Run the process and monitor the results

4. Disable Lazy Load Temporarily

In some cases, native lazy loading or plugin-based lazy loading can interfere with WebP thumbnail rendering. Consider disabling lazy load for images temporarily and testing thumbnails again. You can either modify your theme or use a filter in your functions.php file:

add_filter('wp_lazy_loading_enabled', '__return_false');

Preventing Future Issues with WebP in WordPress

As WordPress continues evolving, core support for modern formats like WebP will improve. However, to reduce the likelihood of WebP thumbnail issues in the future, follow these best practices:

• Use a hosting provider with modern PHP and image libraries
• Regularly update WordPress core, themes, and plugins
• Use reliable image optimization plugins with WebP fallback solutions
• Test image uploads on a staging site before rolling out major media changes

Conclusion

WebP image format offers real performance advantages, but its integration into WordPress still presents occasional challenges. Blank thumbnails in the media library can arise from server misconfigurations, outdated libraries, plugin conflicts, or browser issues. By systematically diagnosing and addressing each potential cause—starting with server compatibility and working down to user-level configurations—these issues can be resolved effectively.

As awareness and usage of WebP increase, so will plugin and theme support. Until then, staying proactive about testing and choosing well-supported tools will help reduce frustration and maintain a premium visual experience on WordPress websites.

FAQ: WordPress WebP Thumbnail Errors

Q: Why don’t my WebP images show thumbnails in the media library?

A: This is typically due to lack of WebP support in the server’s image processing libraries (GD or Imagick), an incompatible plugin or theme, or file permission issues.

Q: How can I verify if my server supports WebP?

A: Create a PHP info file or ask your hosting provider. Look for WebP under the supported formats in the GD or Imagick section.

Q: Can I use WebP images on older browsers?

A: Not directly. You’d need a plugin that provides fallback images for older browsers that don’t support WebP.

Q: Do I need a plugin to use WebP images in WordPress?

A: No, but using a plugin can help with compatibility and provide fallbacks, improved optimization, and thumbnail generation.

Q: What plugin can regenerate WebP thumbnails?

A: The “Regenerate Thumbnails” plugin works well with all image formats including WebP, assuming your server supports thumbnail generation for them.