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Troubleshooting WP Fastest Cache Preload: Common Issues and Solutions

19 threads Sep 16, 2025 Plugin → Wp fastest cache

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The preload feature in WP Fastest Cache is a powerful tool for automatically generating cached versions of your site's pages, ensuring visitors always get a fast experience. However, setting it up can sometimes lead to confusion or unexpected server behavior. Based on common community reports, this guide covers the most frequent preload-related issues and how to resolve them.

Common Preload Issues and Their Solutions

1. High Server CPU Usage from Preload

The Problem: Your web host reports high server load, and the connections are traced back to the WP Fastest Cache preload process.

Why It Happens: The preload feature works by systematically visiting every page on your site to generate its cache. On large sites or on servers with limited resources, this can consume significant CPU and memory.

The Solution: The WP Fastest Cache team suggests reducing the number of pages processed simultaneously. In the preload settings, lower the "Preload (number of pages per minute)" value to a smaller number, such as 2. This will slow down the preload process but will drastically reduce its impact on server resources.

2. Manual Preload URL Returns a Blank Page or "ERROR"

The Problem: You try to manually trigger preload by visiting https://yoursite.com/?action=wpfastestcache&type=preload but get a blank screen, a generic "ERROR" message, or nothing happens.

Why It Happens: This is often caused by server-level security configurations, such as mod_security rules, or a PHP error that is being hidden.

The Solution:

  • Check with your hosting provider to see if any security modules are blocking the request.
  • Ensure that PHP error logging is enabled on your server and check the logs for any specific errors related to this request.
  • Test if the issue persists with all other plugins temporarily disabled.

3. Preload Cron Job Floods the Server with Files

The Problem: After setting up a server cron job, you find thousands of files (e.g., index.html?action=wpfastestcache&type=preload.204622) being created in your server's root or other directories.

Why It Happens: This is almost always due to an incorrect cron job command. Using wget without the proper output flags can cause it to save the HTML response of the preload URL as a file.

The Solution: Use the correct, clean cron command. The following commands will call the preload URL without saving any output files:

wget -O - "https://yoursite.com/?action=wpfastestcache&type=preload" >/dev/null 2>&1
# or using curl
curl -s "https://yoursite.com/?action=wpfastestcache&type=preload" >/dev/null

Important: Ensure the URL in your command is correctly formatted and does not contain any HTML entities like ”.

4. Preload Gets Stuck or Re-caches the Same Pages

The Problem: The preload process seems to work initially but later gets stuck in a loop, continuously caching the same set of pages instead of moving through all of your content.

Why It Happens: Threads indicate that using object caching systems like Memcached can be incompatible with WP Fastest Cache's preload mechanism and cause this looping behavior. It can also occur if a CDN is caching the preload request itself.

The Solution:

  • Disable Memcached: If you are using a Memcached object cache, try disabling it. The plugin's preload feature may not function correctly alongside it.
  • Bypass the CDN: Configure your cron job to call the server's IP address directly (e.g., by editing the server's hosts file for the cron job) to prevent the CDN from serving a cached response to the preload request.

5. Preload Does Not Start After Completion

The Problem: After a preload cycle finishes, subsequent calls to the preload URL only return "Preload Restarted" without actually rebuilding the cache.

Why It Happens: The preload feature is designed to run through all pages. Once it is "Completed," it will not start a new cycle unless the cache is first cleared.

The Solution: To automate full cache rebuilds, your cron job must first clear the cache and then trigger preload. You can use the dedicated cache-clearing URL:

https://yoursite.com/?action=wpfastestcache&type=clearcache&token=YOUR_SECRET_TOKEN

You must define WPFC_CLEAR_CACHE_URL_TOKEN in your wp-config.php file for the security token to work. A suggested cron job sequence is:

  1. Call the clear cache URL.
  2. Wait a few seconds.
  3. Call the preload URL repeatedly until it returns "Completed."

6. Preload Timeout (Curl error 28)

The Problem: The preload process fails for certain slow-loading pages with a "Curl error 28: operation timed out."

Why It Happens: The internal function used for preloading has a default timeout setting of 10 seconds. Any page that takes longer than that to generate will cause an error.

The Solution: You can modify the plugin's code to increase the timeout limit. In the file wp-content/plugins/wp-fastest-cache/wpFastestCache.php, find the wp_remote_get function call related to preload and increase the 'timeout' parameter value (e.g., from 10 to 20). Note: This is an advanced step, and any changes will be overwritten when the plugin updates.

Conclusion

Effectively managing the WP Fastest Cache preload feature often involves fine-tuning its settings to match your server's capacity and ensuring your automation scripts are correctly configured. For persistent issues not resolved by these steps, checking your server's error logs and consulting your hosting provider for specific restrictions is highly recommended.

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