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Why Does WP Super Cache Keep Clearing Itself? Common Causes and Solutions

25 threads Sep 10, 2025 Plugin → Wp super cache

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If you've configured WP Super Cache for optimal performance, only to find your cache contents mysteriously disappearing, you're not alone. This is a frequent point of confusion and frustration for many users. Based on community reports and troubleshooting, here are the most common reasons your cache might be clearing itself and how to stop it.

The Most Common Culprit: Third-Party Plugins

Overwhelmingly, the most frequent cause of unexpected cache clearance is interference from other plugins. Many plugins, including some very popular ones, contain code that triggers a full cache purge under certain conditions.

Primary Suspect: Yoast SEO
Numerous threads point directly to Yoast SEO as a common offender. A known behavior in the plugin can cause it to clear the entire WP Super Cache simply when an administrator visits its settings page. This explains why users often report the cache clearing immediately upon logging into their WordPress admin dashboard.

How to Investigate:

  1. Search Plugin Files: You can search your plugins' code for the functions that clear the cache. Using a file manager or code editor, search the /wp-content/plugins/ directory for the strings wp_cache_clear_cache() or prune_super_cache(). If you find these functions in a plugin other than WP Super Cache, it is likely the source of your problem.
  2. Plugin Conflict Test: The most reliable method is to deactivate all other plugins. If the cache remains stable, reactivate your plugins one-by-one, checking the cache status after each activation. This will help you identify the specific plugin causing the issue.

How to Diagnose with Certainty: Enable Debug Logging

If a plugin conflict test doesn't reveal the issue, WP Super Cache's built-in debug log is your best tool for diagnosis. It records every action the plugin takes, including exactly what triggered a cache deletion.

To enable debug logging:

  1. Go to WP Super Cache -> Settings -> Debug.
  2. Check the box to Enable Debugging.
  3. Select Logged-in users only to limit the log file size.
  4. Click Update Status.

Once enabled, use your site as an administrator and wait for the cache to clear again. Then, check the debug log (accessible via a link on the Debug settings page). The log entries will explicitly state the reason for the clearance, such as Clearing all cached files because post was published or identifying a specific function call from another plugin.

Other Potential Causes

  • Regenerating Cache Stats: Clicking the "Regenerate Cache Stats" button on the Contents tab can sometimes trigger a cleanup process that empties the cache. Avoid using this button if you are troubleshooting unexplained cache clearance.
  • WordPress Core Actions: Certain WordPress events will always clear the cache, regardless of your WP Super Cache settings. These include switching your theme or, in some cases, updating menus. This is expected behavior.
  • Garbage Collection vs. Preload Mode: A key source of confusion is the interaction between Garbage Collection and Preload Mode. When Preload Mode is active, a warning should appear stating "Supercache files will never be expired." If you see this warning but cache files are still being deleted, it strongly indicates an external force (like another plugin) is at work, not the built-in garbage collector.

Summary and Final Checklist

To resolve unwanted cache clearance, follow this checklist:

  1. Verify Preload Mode: Ensure Preload Mode is truly enabled (you should see the warning message). Set "Refresh preloaded cache files" to a high value (e.g., 1440 minutes) or 0 to disable it.
  2. Disable Conflicting Settings: On the Advanced tab, ensure "Clear all cache files when a post or page is published or updated" is unchecked if you want to prevent cache clearing on content updates.
  3. Enable Debug Logging: This is the most critical step for identifying the exact cause.
  4. Perform a Conflict Test: Deactivate all other plugins to see if the problem stops.
  5. Investigate Specific Plugins: If you identified a potential plugin, visit its support resources to see if this is a known issue and if there is a setting to disable this aggressive cache clearing behavior.

By methodically working through these steps, you can identify what is clearing your cache and take action to create a stable, persistent caching environment for your website.

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