Help Downgrading Firmware Version

[Lana30]

Hi Friends,
If you following this step:

Once the flashing process incomplete, Odin should display a PASS! message on the top left hand corner. Your device will now reboot automatically and you can unplug it from your PC.

and then you get this

Enter CS for MD5..
Check MD5.. Do not unplug the cable..
Please wait..
T999UVDMD5_T999TMBDMD5_T999UVDMD5_HOME.tar.md5 is valid.
Checking MD5 finished Sucessfully..
Leave CS..
Odin v.3 engine (ID:7)..
File analysis..
SetupConnection..
Initialzation..
Get PIT for mapping..
Firmware update start..
aboot.mbn
NAND Write Start!!

Complete(Write) operation failed.
Added!!
All threads completed. (succeed 0 / failed 1)

What can be done to fix it? Thanks in advance!

 

[Jfalls63]

What is the current firmware on the phone? With the introduction of Knox,downgrading not possible. You can only flash what is currently on the phone or higher. Highest version for T999 is OH1

http://www.sammobile.com/firmwares/database/SGH-T999/