g920f cert file write error

Phone must be rooted!
If the software can’t root the phone automatically,
then you must root your device manually.
1. Power on the phone.
2. Tap 7 times on ‘Build number’ in ‘Settings’-‘About phone’ to enable ‘Developer options’,
go to ‘Settings’-‘Developer options’ and enable ‘USB debugging’.
3. Connect the phone to PC with USB cable, install drivers if needed.
4. Select device in ADB settings.
5. Press ‘Read EFS’ button to read backup or ‘Write EFS’ to restore.
6. Press ‘Read CERT’ button to read certificates or ‘Write CERT’ to restore.
7. Press ‘Write NV DATA’ if you need to restore NV backup.

Operation: Write CERT
Selected model: SM-G920F
Software version: 26.9

Waiting ADB device…
Please, allow USB debugging on phone… OK
Reading phone info…
Model: SM-G920F
Android version: 6.0.1
Product code:
Phone version:
PDA version: G920FXXU4DPHB
CSC version: G920FBTU3DPB1
CSC country code: UK & IRE
CSC sales code: BTU
HW version:
Phone SN: 00000000000
Modem board:
RF cal date:
Checking Super user right… true
Initialization zTool… OK
Running zTool, please wait…
Start… OK
Initialization… OK
Generate and check client proof… OK
Verify proof by client… OK
Reading data… error (8)

Done with Samsung Tool PRO v.26.9