#1.0 This guide is for use on un-rooted and rooted phones. The following procedures from #1.3 onwards can also be used on non Lollipop firmwares. Introduction Without a doubt, the upgrade to Android 5, Lollipop, is one of the biggest things to happen to Android since its launch. Make no mistake... this is a major firmware upgrade and it introduces a number of new features, not the least of which is ART, (Android RunTime), that replaces Dalvik and which, from my own experience, improves battery life and performance considerably. In a nutshell, Dalvik is a JIT, (Just In Time), compiler that operates on each app as it is needed whilst ART does it all just the once, Ahead Of Time, (AOT). This is why, after the initial update, the first boot will take a lot longer than usual whilst ART optimizes each app for the first time. This saves both battery and improves performance. For more information on ART see, Android Runtime. #1.1 The 3 important things to do NOW, before any update are... BACKUP, BACKUP and BACKUP everything on your phone's internal and external, memory. You have been warned! For more information on backing up, see #2.1 (Don't come crying on here if you have failed to take this very, basic, sensible precaution with your valuable data... you've only got yourself to blame! ) #1.2 Why you may be experiencing problems ART does not come without a price and that price is space on your phone's internal memory. Since ART compiles in advance it requires, roughly, about 10% more memory than Dalvik. Therefore, if your phone's internal memory is already chock-a-block full you should make some space as I predict that lack of space will cause more than a few problems initially with this update! Also, when you upgrade not only is the firmware changed but all your app's and settings have to be reconfigured and integrated into the new upgrade during the process. This is in an attempt by Samsung to retain everything on your phone so that you do not have to set it all up again after the change. If you stop and think about the millions of app's and the myriad of settings that this has to take into account then maybe you can understand why there are sometimes problems with phones after new firmware is installed. Some of these problems are caused by app's or settings that are not suitable for the new firmware. Remember, not all app's/games on the Play Store may be compatible with your new firmware yet. This is down to the developers of those apps who have had 6+ months notice to update them. Most have, some have not. Other app's, that work on your existing firmware, have to be updated for the new one, if possible, during the change over. No mean feat... particularly if you've moved apps to your SD card as the system folders for these apps will usually remain on your internal storage and this can cause big problems with separated app and data. These problems can manifest themselves in all sorts of ways, such as... Boot loops App's continually running High battery usage Over heating Storage being eaten up Forced Closes Screen lags High RAM usage Screen freezes Shut-downs These can all occur because the user app's or data have not, or can not, be integrated successfully into the new framework automatically during the change over. Also, the downloaded firmware update itself may have been corrupted. This can easily happen with OTA, (Over The Air), updates where an interruption has occurred with the download. This has also been reported by some who have used the Samsung PC suite, Kies. #1.3 Wiping the Cache Partition Wiping the cache partition is a useful option to use, particularly after a firmware update as it will clear out any rubbish left over from the previous firmware. It can also get you out of problems if you are experiencing a boot loop. This is, again, very simple to do and does not affect any user data on your phone. See video... Wipe cache partition error on Samsung Galaxy S4 Step #1 Turn your phone OFF. Step #2 Boot into Recovery Mode:- Press and hold, simultaneously, the Volume UP + Power buttons until you see some small, blue, writing appear in the top left hand corner of the screen and release immediately. Step #3 You will then see the small, stock, Recovery menu. Using the Volume UP and DOWN buttons, navigate to the menu item, "wipe cache", or, "wipe cache partition", depending on your model. Step #4 Once the option is highlighted you can use the Power key to enact the wipe and reboot your phone. #1.4 Safe Mode: Is it Firmware or User App problems? Safe Mode on your phone is roughly the same as on you PC. It will boot your phone up and load only the default apps that came with the firmware. It does not install your own downloaded apps. Can also be useful for getting out of a bootloop and allowing you to un-install a problem app. This is very useful for determining whether the firmware is to blame for your problems or if it is down to your own apps and settings. This is not a dangerous procedure and can be done very easily. See the following video... Galaxy S4 Tips and Tricks Android Safemode Boot If you encounter the problems whilst in Safe Mode this would indicate that you probably have a bad update and should refer to #2.7 in post #2. #1.5 User Apps: Wiping cache, data and uninstalling Sometimes a particular app or apps that you have installed, are causing problems and are shown to be doing so, on the phone. In the first instance, you can go to... Settings > More > Applications > Downloaded (The route may vary depending on your model of phone and firmware). Step #1 Navigate to the user app, (see *** for System apps), that you believe is the problem and open it and select, "Clear cache". This will clear the apps temporary cache and you can see if that has helped. See video on cache clearing... Wipe cache partition error on Samsung Galaxy S4 Step #2 If not, you can repeat the above steps and this time select, "Clear data". This will clear your user settings for this app and you will need to re-enter the settings again. Check to see if this has solved your problem. Step #3 If not, repeat Step #1 but this time, "Clear cache", "Clear data", and, "Uninstall", the app. Reboot your phone and, if desired, re-install the app from the Google Play Store and re-configure the settings. *** WARNING! Step #1 can also be used on System apps but be very careful about using Step #2 unless you know exactly what you are doing and Step #3 and/or, "Disabling", apps can be extremely dangerous and render your phone a brick on System apps. #1.6 Battery re-calibration Sometimes, after receiving an update, users complain that their battery is being eaten up. This is quite common as the update can affect the battery chip in the phone, causing it to give unreliable readings. These readings usually self correct over a number of charge cycles however, you can re-calibrate your battery by downloading, free from the Play Store, Battery Calibration and following the simple instructions in the app. This should not be used on a regular basis as the battery should never be fully discharged normally. #1.7 Uninstall any Task Killers You do not need to run task killers on Android and they can cause more problems and a lag in performance... Android Task Killers Explained: What They Do and Why You Shouldn't Use Them If you have tried all the above and your phone is still not right, you will need to do a Factory Data Reset, as shown in the next post, #2.