You can now flash XXUGNH4 Android 4.3 on Galaxy S3 I9300 which is the latest official JB update for the S3. The I9300XXUGNH4 update brings bug fixes, minor enhancements, and usual maintenance upgrades. While you may be waiting for the KitKat to beautify your smartphone, it has become a very unlikely update to expect from Sammy. However, you can update the Android 4.4 KitKat latest firmware using various custom firmwares that are both stable and provide amazing performance. Here are some:

• How to Update Galaxy S3 i9300 to Android 4.4.4 with C-RoM
• Update Galaxy S3 i9300 to Android 4.4.4 CM11 M8 Custom ROM – How to
• Update Galaxy S3 I9300 to Android 4.4.2 Fusion-SP Custom ROM – How to
• Update Galaxy S3 I9300 to Android 4.4.2 Revolutionary S5 Custom ROM – How to

XXUGNH4 Android 4.3 Jelly Bean details:

Model: GT-I9300
Model name: GALAXY S III
Country: Netherlands (Vodafone)
Version: Android 4.3
Changelist: 2735602
Build date: Mon, 18 Aug 2014 11:47:53 +0000
Product Code: VDF
PDA: I9300XXUGNH4
CSC: I9300VFGGNH2
MODEM: I9300BUUGNF1

Follow this detailed guide to flash I9300XXUGNH4 Android 4.3 on Galaxy S3 I9300. Once you have updated, here is how to root: Root XXUGNH4 Android 4.3 Jelly Bean on Galaxy S3 I9300 – How to

Prerequisites to flash I9300XXUGNH4 Android 4.3:

Please check these prerequisites before going forward to the update guide.

• Download and install USB drivers for Galaxy S3 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 S3 I9300 carries more than 70% of charge.

Steps to flash I9300XXUGNH4 Android 4.3 on Galaxy S3 I9300:

Required files: download I9300XXUGNH4 for Galaxy S3 from here. Also, download the Odin3 v3.09 for installation from here.

Here are the steps to flash I9300XXUGNH4 Android 4.3 on Galaxy S3 I9300 official firmware:

• Unzip Odin on your computer and install it.
• Unzip firmware zip file in the same folder as Odin.
• Switch your Samsung Galaxy S3 off and boot it in Download mode: press and hold Volume Down, Power and Home buttons together.
• Connect your smartphone with computer. 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).
• On your Odin, select files:
  • lick 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. 
• Make sure to check Auto Reboot and F.Rest Time. Check Re-Partition only if you selected the .pit file.
• Click on Start to initiate the update process.
• When Android 4.3 JB update installation is successfully completed, you will get a PASS message.
• Once you see the home screen, you can disconnect your Samsung Galaxy S3 and reboot it.