After each OTA Android upgrade, I get a message saying "Optimizing app x of xxx" that takes a while. The last time I upgraded, the battery ran out during the optimization process (not during the upgrade itself, which I know it's dangerous). After rebooting the phone the "optimization" process didn't carry on.

So, how can I start that process by itself without upgrading anything? (my Android is already up to date).

  • 1
    Are you facing a problem in the device?
    – Firelord
    Commented Mar 14, 2016 at 19:05
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    Well, not really, but since the "app optimization" was interrupted, I thought it would be a good idea to actually finish it.
    – OMA
    Commented Mar 14, 2016 at 19:25
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    I believe any un-optimized apps will be optimized on their first run, if they haven't been already. Commented Mar 14, 2016 at 21:49
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    @MatthewRead Eldarerathis once analyzed what that optimization does. Basically it re-creates the Dalvik (or now ART) cache for each app, dropping the old version and re-creating it with the updated engine (it "invokes the dexopt utility on all of the applications that need it."). So you should be right. If I had designed that process, I'd first drop the entire cache and then walk the apps – so that, if interrupted, the first start of the remaining ones would take care for the remains.
    – Izzy
    Commented Mar 14, 2016 at 22:58
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    @OMA because at upgrade time, the user "expects" to wait – while not expecting each app to "start that slow" directly after the upgrade?
    – Izzy
    Commented Mar 14, 2016 at 23:01

1 Answer 1


Go into the recovery (you need to boot the phone while pressing several buttons - you'll need to google which one is set for your device - an example would be Volume down + Home) and delete the "Dalvik cache". Then restart your phone. Now the optimizing process should start again.

But I personally recommend to not do that - it can't hurt, but if your phone works well you don't need this, because it's just like a Backup of your app installation files.

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