The invention detects a full browser cache using multiple requests for the same page from a known URL. A request to the URL returns a page with a randomly or pseudo-randomly generated number. A request and then a re-request is made for the same page. If the cache is operating normally, the page for the re-request will be obtained from the browser cache and the number in the first request response will match the number from the re-request response. If the cache is not properly storing pages, the page will be fetched from the URL and contain a different randomly generated number, and therefore, the number in the two responses will not match. The user is notified and may be pointed to information explaining how to empty the cache.