samsung n910h failed to write cert file please help

Platform: Samsung Android
Selected port: COM7
Selected model: SM-N910H
Selected file: C:\Users\Dali\Downloads\Cert-sm-n910c-355025060395777.cert
Detected phone model: SM-N910H
Firmware compiled date: Wed Oct 28 20:49:42 KST 2015
PDA version: N910HXXU2COJ4
CSC version: N910HOJV2COJ1
SW version: N910HXXU1COJ2
Android version: 5.1.1 (LMY47X)
Checking Root:
Phone is Rooted.
Reading security backup, please wait…
Phone will restart now. Please don’t disconnect cable!
Perform the following steps:
1. Connect phone via UART cable to the Box.
2. Note: phone screen must be active
Connecting to phone, please wait…
Writing Certificate failed