[OnePlus 5 Questions & Answers] simo6:
the log:

I:operation_end - status=0

I:Set page: 'backup'

I:Set page: 'backupencryption'

I:Set page: 'backup_options'

I:Set page: 'backup'

I:Set page: 'backup_run'

I:operation_start: 'Nandroid'

Updating partition details...

I:Data backup size is 9064MB, free: 95716MB.

I:Unable to mount '/usb_otg'

I:Actual block device: '', current file system: 'vfat'

...done

I:Backup Name is: '2017-12-30--17-01-48'

I:Backup_Folder is: '/data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48'

I:Calculating backup details...

* Total number of partitions to back up: 13

* Total size of all data: 12729MB

* Available space: 95716MB

[BACKUP STARTED]

* Backup Folder: /data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48

Backing up Boot...

I:Reading '/dev/block/sde19', writing '/data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48/boot.emmc.win'

I:Restored default metadata for /data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48/boot.emmc.win

I:Partition Backup time: 0

Invalid encryption mode 'ice:aes-256-cts'

Backing up Cache...

Invalid encryption mode 'ice:aes-256-cts'

I:Creating backup...

I:Creating tar file '/data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48/cache.ext4.win'

I:Using compression...

I:addFile '/cache/recovery' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/last_log.1' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/log' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/last_log' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/last_install' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/last_bootloader_log' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/last_kmsg' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/.version' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/recovery.fstab' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/recovery/storage.fstab' including root: 0

==> set selinux context: u:object_r:cache_recovery_file:s0

I:addFile '/cache/backup_stage' including root: 0

==> set selinux context: u:object_r:cache_backup_file:s0

I:addFile '/cache/backup' including root: 0

==> set selinux context: u:object_r:cache_private_backup_file:s0

I:addFile '/cache/log_before_911' including root: 0

==> set selinux context: u:object_r:cache_file:s0

I:addFile '/cache/log_before_911/android_911.log' including root: 0

==> set selinux context: u:object_r:cache_file:s0

I:addFile '/cache/log_before_911/kernel_911.log' including root: 0

==> set selinux context: u:object_r:cache_file:s0

I:addFile '/cache/log_before_911/android_911.log.1' including root: 0

==> set selinux context: u:object_r:cache_file:s0

I:addFile '/cache/log_before_911/android_911.log.2' including root: 0

==> set selinux context: u:object_r:cache_file:s0

I:addFile '/cache/log_before_911/kernel_911.log.1' including root: 0

==> set selinux context: u:object_r:cache_file:s0

I:Closing tar

I:pigz process ended with RC=0

I:Thread id 0 tarList done, 0 archives.

I:Thread ID 0 finished successfully.

I:InfoManager saving '/data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48/cache.info'

I:createTarFork() process ended with RC=0

I:Partition Backup time: 0

Backing up Recovery...

I:Reading '/dev/block/sde22', writing '/data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48/recovery.emmc.win'

I:Restored default metadata for /data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48/recovery.emmc.win

I:Partition Backup time: 1

Invalid encryption mode 'ice:aes-256-cts'

Backing up System...

Invalid encryption mode 'ice:aes-256-cts'

Error opening: '/system/app/DeskClock/oat/arm64' (Not a directory)

I:Error in Generate_TarList!

Error creating backup.

I:InfoManager saving '/data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48/system.info'

createTarFork() process ended with ERROR: 255

Backup Failed. Cleaning Backup Folder.

I:Copying file /tmp/recovery.log to /data/media/0/TWRP/BACKUPS/b7d162d2/2017-12-30--17-01-48/recovery.log