Sony Mobile has released Android 4.4.2 KitKat for Xperia Z1, Z Ultra and Z1 Compact but the firmware brings limitation on microSD card usage. It relates to the third-party apps inability to write on SD cards.
Android KitKat Flaw
Sony's new firmware update deliver lots of features on three Xperia smartphones such as user interface, intense app updates and exclusive services. However, Android KitKat has a major flaw related to microSD card functionalities.
According to Xperia Blog, owners of Xperia Z1, Z Ultra and Z1 Compact should first be aware of the microSD card limitation found on Android KitKat software. Third-party apps are unable to write on SD cards among Xperia devices running Android KitKat version and it means several apps are incapable of doing the following:
1. Third-party file managers cannot copy files onto your SD card over a network.
2. TomTom app for downloading maps to the SD card is no longer possible.
3. Requires rooting to bypass Android Kitkat limitation on SD cards.
Sony's first-party app called File Commander is not affected by this limitation however, the app itself do not feature advance options compared with other third-party file managers such as ES Root Explorer.
Basically, you need to gain access for your Xperia smartphones in order to bypass the limitation delivered by Android 4.4.2 KitKat update. Once you have rooted your Xperia device, you can install an app from the Play Store called "SDFix: KitKat Writable MicroSD" to allow third-party apps to write again on your SD card.
However, rooting tool kits for Xperia Z1, Z Ultra and Z1 Compact running Android 4.4.2 KitKat remains scarce and developers are still creating safe rooting kits for these devices.
Another possible way to get around the limitation is to create a dedicated private folder on the SD card which the app can write to. This technique is usually performed by third-party developers but the drawback is once the app has been uninstalled on the device, all data written on the private folder will also be deleted.
SDFix: KitKat Writable MicroSD app is available and free to download at the Play Store. It requires root access in order to be used by your Xperia handset to restores it by modifying a configuration file.
The app also advises individuals regarding warranty for root access will void that and only suggestive on devices running stock ROM. Customised firmware can always write data on the SD card without any limitations. It has been updated on March 17th and file size is only 396 KB.