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Why WP Super Cache Test Fails: Troubleshooting the 'Timestamps Differ' Error

39 threads Sep 16, 2025 Plugin → Wp super cache

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Understanding the WP Super Cache Test Failure

A common and often confusing issue reported by users of the WP Super Cache plugin is the cache test failure. When you click the "Test Cache" button, you might receive an error message stating: "The pages do not match! Timestamps differ or were not found!".

This error indicates that the plugin's internal test, which requests your homepage twice and compares the timestamps in the generated HTML comments, found a discrepancy. A successful test would show matching timestamps, proving that the same cached page was served for both requests.

Why Does This Cache Test Error Happen?

Based on community reports and troubleshooting threads, several underlying causes can trigger this error:

  • Server Configuration Issues: The most common cause is that the server cannot make HTTP requests to itself. This is often due to security restrictions, firewall rules, or misconfigured local DNS. The test failure in Thread 19 showing a 403 Forbidden error is a classic example.
  • SSL Certificate Problems: If your site uses HTTPS, a missing or misconfigured SSL certificate on the server can prevent the internal cURL request from completing, resulting in errors like the cURL error 60 seen in Thread 14.
  • Conflicting Caching Layers: The presence of another caching mechanism, such as Cloudflare (Thread 6) or a server-level cache, can interfere. These layers might serve their own cached version or strip the HTML comments WP Super Cache relies on for the test.
  • PHP Configuration: In rare cases, as hinted at in Thread 5, a discrepancy between the master and local values for a setting like date.timezone in PHP could cause timestamp generation issues.
  • Debug Settings Not Enabled: The test cannot function unless the "Cache Status Messages" option is enabled in the plugin's Debug settings, a problem highlighted in Thread 10.

How to Troubleshoot and Resolve the Issue

Since the automated test can be unreliable, the recommended approach is to perform a manual test. This method, often suggested in the support threads, is the most accurate way to verify caching is working.

Step 1: Enable Cache Status Messages

  1. In your WordPress dashboard, navigate to Settings → WP Super Cache.
  2. Click on the Debug tab.
  3. Check the box for Enable Cache Status Messages.
  4. Scroll down and click Update Status.
  5. Finally, clear the site cache from the Contents tab.

Step 2: Perform a Manual Cache Test

  1. Open a new Incognito (Chrome) or Private (Firefox) browser window. This ensures you are viewing the site as a logged-out user, which is who the cache is designed for.
  2. Navigate to your website's homepage.
  3. Right-click on the page and select View Page Source.
  4. Scroll to the very bottom of the HTML code. You should see a comment like: <!-- Cached page generated by WP-Super-Cache on 2024-01-15 10:30:45 -->
  5. Take note of this exact timestamp.
  6. Without closing the window, simply refresh the page.
  7. Right-click and View Page Source again. Scroll to the bottom and check the timestamp.

Interpretation:

  • If the timestamp is identical in both views, congratulations! WP Super Cache is working correctly. The automated test failure is a false positive, and you can ignore it.
  • If the timestamp changes on every refresh, caching is not working. Proceed to the next steps.

Step 3: Advanced Troubleshooting

If the manual test shows caching is not working, consider these common fixes:

  • Check with Your Hosting Provider: Contact your host and ask if they block loopback connections (a server making requests to itself). This is a frequent cause. Mention the 403 Forbidden or connection errors from the cache test.
  • Verify SSL Certificate: Ensure your SSL certificate is properly installed and valid on the server itself, not just for public visitors.
  • Temporarily Disable Other Caching: If you use Cloudflare, try temporarily pausing it or enabling Development Mode. Also, check if your host has a built-in cache and ask how it interacts with plugins like WP Super Cache.
  • Review .htaccess Files: Ensure the WP Super Cache modification rules are correctly present in your root .htaccess file and the wp-content/cache/.htaccess file.

Conclusion

While the "Timestamps differ" error in the WP Super Cache tester can be alarming, it is often a red herring. The plugin's automated check is sensitive to server configurations that have no impact on actual visitor caching. The most reliable method to confirm functionality is the manual test using an incognito window. If that test passes, your site is being cached correctly for your users, and you can safely disregard the failed automated test.

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