[Q] Cannot encrypt Tab S 8.4

[dl12345]

I would have posted this in the thread for the ROM in question, but due to new user restrictions I cannot post in the development forum.

I have flashed the NF9 ROM to my GTS 8.4. I'm now wanting to encrypt the device. I've set a password (not a pin, but a password). I select the option to encrypt, enter the password, and up comes the black screen with the green android. It stays this way for about 5 - 10 minutes and then the device reboots.

No warning, no error message. Just a normal reboot. And the device is not encrypted. I've tried to select the fast encrypt option, however this has no effect and the same behavior ensues.

Anyone else seen this before? I'm not sure if it is ROM related...

 

[dl12345]

After flashing a stock, unrooted ROM, I found that I was able to encrypt no problem. As soon as I rooted using CF-Auto root, encryption failed. Even worse, if you try to encrypt first and then root afterwards, the root appears to work but the device gets soft bricked. I tried multiple different root methods, but currently only CF-Root works.

Some searching indicates that this problem with encrypting the device when rooted happens on other Samsung devices

http://forum.xda-developers.com/showthread.php?t=2487018
http://forum.xda-developers.com/showthread.php?t=2769248

A further search showed that member bruzzy recently came up with a workaround that also works for the SM-T700:
http://forum.xda-developers.com/showthread.php?t=2791587

I followed bruzzy's procedure with a stock rom, but it would probably work with any ROM given that the cause is SuperSU. The procedure on a stock ROM would be

• flash stock rom with odin
• root with cf-auto root
• run supersu - say no to knox disable as it hangs and doesn't seem to disable properly
• either on the host pc run adb shell then su or do the same with terminal emulator
• disable knox by typing the command "pm disable com.sec.knox.seandroid"
• temporarily disable supersu by unchecking the "Enable Supersu" option in settings
• reboot
• encrypt the device
• reboot the device into odin mode
• flash twrp
• boot into recovery
• mount /system
• open the console
• cp /system/xbin/daemonsu /system/xbin/su
• /system/xbin/su --install)
• restart

Now, be aware the TWRP does not see the encrypted data partition, instead throwing errors, so you cannot access your internal storage from within recovery. Furthermore, using different roms, whenever I made a nandroid to external sd, on reboot the backup was deleted. As a result, I was forced to make a backup to usb otg. Overall, having an encrypted device just seems like a lot of trouble. A factory reset of the encrypted device will require you to reflash stock recovery as twrp does not do the reset properly.