[Galaxy S 4 General] cefkiller:
:laugh:Hello guys,

This is my first tutorial on the XDA-developers forum, in order to improve myself and be more efficient, do not hesitate to comment, or ask questions, I will be more then happy to answer since I have spent so much time on this, using two different I9505, mine and my boss's. So without further ado, let's get started :p

Here is a full guide on how to downgrade your I9505 from 4.4.2 to 4.3. KNOX WILL TRIGGER, there are other tutorials that show how to downgrade 4.4.2 to 4.3 without triggering the knox, I will explain some of them, but they are not 100% successful.

Do it on your own risk, neither me nor XDA-developers will be responsible if you brick or damage your phone.​

Nevertheless, if you follow those exact steps, you won't have any problem (you may actually have some, but we can solve them together).

Requirements:

Samsung galaxy S4 I9505

Rooted phone

CWM or any custom Recovery

CyanogenMod 10.2.1 [click here] (jellybean 4.3.1) or any other custom with its proper kernel

Google apps jellybean [here]

(May need) Modem FNC4 or any above FNB8 [here]

(May need) Pit File to resolve some problems [here]

[KNOX 0x1 (triggered) WORKS 100%]

[Step 1: Optional, only if you can root your phone]

Before we start, I advice you backup your phone, save your EFS folder which contains your IMEI and other "sensitive information" related to your phone:

To do that, first you need to root your phone, then use a file explorer such as "ES FILE EXPLORER".

[IMG="Root enabled"]http://img11.hostingpics.net/pics/825295841.png[/IMG]​

Go to your explorer and turn on "root explorer".

Once you have done that, go to your root folder.

Copy the folder called EFS to your SD Card.

(Optional)Make another copy on your HDD or file-hosting provider.

[Step 2: Installing the rom]

Copy your CyanogenMod or any other 4.3 custom fw + Google apps into your sdcard

Shutdown your phone

Press and hold down volume up, home button and power button to start in recovery mode (for about 5secondes)

Wipe data/cache (if you have philztouch, chose that you will install a new rom) and press YES

Advanced -> Wipe dalvik cache YES

Install zip from sdcard -> chose cyanogenmod zip file -> YES

Install zip from sdcard -> chose gapps zip file -> YES

Reboot your computer.

[Step 3: Resolving some problems]

If the phone application crashes whenever you try to make a phone-call, then you should flash your modem.

1.Shutdown you phone.

2.Press and hold down volume down, home button and power button to start in download mode until you see the confirmation, then press up to continue

3.Plug your micro usb cable into your phone, go to odin

4.Select modem (or CP for odin 3.09) and select the modem file

5.Uncheck Autoreboot

6.Click Start

7.Once done, unplug your cable, take off the battery, put it back, redo steps 2 to 4

8.Check this time Autoreboot and Start the process

If you flash your phone and you don't have the sound, then I advice you go back to 4.4.2, and follow this guide from the beginning

[KNOX 0x0 (not triggered) WIFI OFF]

I do see the point to go back to 4.3 (a lot of applications don't work properly on Kitkat + better performances for the S4 on Jellybean), however, I don't know if someone can use his phone without the wifi. Anyway, if you want you can try this method, for simply go back to 4.3, use saferoot and install mobile odin to go to 4.4.2 rooted, without triggering the knox (be aware that there is a simple method which roots the 4.4.2 but this doesn't work on newer 4.4.2).

I remind you that KNOX triggers only if you use a custom rom or modified kernel, in that case Knox turns to 0x1, and this cannot be undone.

Instead of writing my method, I find out two threads on xda.

First one, you cannot make phonecalls unless you flash the modem, and then you won't have the wifi anymore.[here]

Second, not tested yet, but it is promising, you can find out [here]

That's it guys, hope this will help you find your happiness.