Answered: Offline app updated works perfect on iOS - not so perfect on Android
Created a ST 2.1-RC2 application, compiled it using Sencha Cmd 3.0.0 and uploaded it to the server. Did a change and built it again using Sencha Cmd. Works perfect on iOS devices - the "Application updated - reload" message is shown and then new version is available after page reload. Also works perfect in Chrome on Windows.
Sadly no luck on android phones from Sony (running both 2.3.6 and 4.0.6) where the app is still showing the old version. Nothing less than clearing the offline cache makes the browser pick up the new version.
I had the same issues.
Sencha by default names the manifest file cache.appCache.
Some Android browsers don't like this (Galaxy S3).
Change the name of the file to 'cache.manifest' . That worked for me.