The cache.manifest file may itself be cached by the browser.
If you’re unable to force the browser to refresh its application cache, try clearing the regular browser cache. You could also change your server settings to send explicit instructions not to cache the cache.manifest file.
For Apache web server , you can tell Apache not to cache the cache.manifest file by adding the following to your .htaccess file:
tells Apache to only apply the rules that follow to the cache.manifest file.
The combination of ExpiresActive
On and ExpiresDefault
"access" forces the web server to always expire the cache.manifest
file from the cache. The effect is, the cache.manifest file will never be cached by the browser.