This plugin has a cache tester built into the settings page. The tester sends two requests to the homepage. It records the timestamp in the source of the page each time and then compares them to make sure the second attempt was cached.
Sometimes the tester fails. This usually happens when the server is not configured correctly or there are strict security rules blocking those requests, and it can’t send a request to itself.
In those cases you need to test the caching manually but it’s easy to do:
- In the Debug settings page of the plugin make sure that “Cache Status Message” is enabled.
- Open a private/incognito browser window and load your website.
- View the source of the page and examine the timestamp at the end of the page. It should look like:
<!-- Dynamic Page Served (once) in 0.829 seconds --> <!-- Cached page generated by WP-Super-Cache on 2009-01-12 16:11:54 --> <!-- Compression = gzip -->
- Force reload the page (shift-reload) and view the source again.
- Confirm that the timestamp matches what you saw when you loaded the page for the first time.
- If timestamps do not match then enable debugging in the plugin. The debug log should tell you why a cached page wasn’t saved or served.