Samsung released XXUGNH4 Android 4.4.2 for Samsung Galaxy S4 i9500. Based on the previous Android KitKat, the update brings new drivers and system enhancements. The latest update is deemed essential for system reliability but is currently only available in Russia as an OTA update. Here is how to flash XXUGNH4 Android 4.4.2 on Galaxy S4 i9500 manually. 

XXUGNH4 Android 4.4.2 details:

Model: GT-I9500
Model name: GALAXY S4
Country: Russia
Version: Android 4.4.2
Changelist: 2548731
Build date: Tue, 19 Aug 2014 10:06:19 +0000
Product Code: SER
PDA: I9500XXUGNH4
CSC: I9500SERGNH4
MODEM: I9500XXUGNF6

Prerequisites to flash XXUGNH4 Android 4.4.2 on Galaxy S4 i9500:

• Download and install USB drivers for SGS4 in your computer.
• Make sure to take backup of any important files on your smartphone.
• Enable USB debugging option by pressing Menu > Settings > Applications. Navigate and tap on Developer Options to ensure that USB Debugging is enabled.
• Ensure that your Samsung Galaxy S4 i9500 carries more than 70% of charge.

How to flash XXUGNH4 Android 4.4.2 on Galaxy S4 i9500 official firmware:

Required files: download the XXUGNH4 Android 4.4.2 firmware file from here. Extract and you will get a tar.md5 file. Also download the Odin3 v3.09 for installation from here.

Here are the steps to help you flash XXUGNH4 Android 4.4.2 on Galaxy S4 i9500.

• Install Odin on your computer.
• Switch your Samsung Galaxy S4 off and boot it in Download mode: press and hold Volume Down, Power and Home buttons together. When connected successfully, you will get a message in Odin saying Added!!. (In case you don’t get it, try another USB port. If that doesn't help either, then re-install USB drivers).
• In Odin make sure that the Auto Reboot and F. Reset Time check boxes are the only options checked and nothing else is.
• On your Odin, select files:
  • Click on AP / PDA and select file with CODE in its name.
  • Click on CP/Phone and select file with MODEM in its name - ignore if you didn't get any such file. 
  • Click on CSC and select file with CSC in its name - ignore if you didn't get any such file.
  • Click on PIT and select the .pit file - ignore if you didn't get any such file. 
• When official update installation is successfully completed, on Odin ID:COM will turn green and Odin will show you a PASS message.
• Samsung Galaxy S4 I9500 will restart automatically and you can then disconnect your device from computer.

Note: In case your device gets stuck at boot screen after installation of official firmware, perform data wiping tasks: turn off S4 and reboot it into recovery mode. In recovery, select the wipe data/factory reset. Go back and reboot your smartphone.