backup abort because of chown

[the-matzup]

Bug-Report
When I perform a backup with ncp-backup, the process is aborted with the following error message:
chown: changing group of '/media/USBdrive/ncp-backups/nextcloud-bkp_20191003_1570136572.tar': Operation not permitted Abort...

By deleting the following line in the ncp-backup script, the backup function works fine again (I don't know why the user group has to be changed for the backup):
chown :www-data "$destfile"

System information
NextCloudPi version v1.17.1
NextCloudPi image NextCloudPi_07-21-19
distribution Raspbian GNU/Linux 10 \n \l
automount yes
USB devices sdb sdc
datadir /media/myCloudDrive/ncdata
data in SD no
data filesystem btrfs
data disk usage 1.2G/120G
rootfs usage 2.1G/7.1G
swapfile /swap
dbdir /var/lib/mysql
Nextcloud check ok
Nextcloud version 16.0.5.1
HTTPD service up
PHP service up
MariaDB service up
Redis service up
Postfix service up
internet check ok
port check 80 closed
port check 443 open
IP REMOVED SENSITIVE VALUE
gateway REMOVED SENSITIVE VALUE
interface eth0
certificates REMOVED SENSITIVE VALUE
NAT loopback no
uptime 2:01

[nachoparker]

Thanks for repoting. I don't see why changing the group would not be permitted, as long as it is not a windows filesystem, which is not supported.

[nocin]

I had the same issue doing backups on an ZFS share I have mounted to my NextcloudPi.
So my situation is a little different, but if anyone ends up here, this was my solution:

The problem is since ZFS on Linux 0.8.3 the no_root_squash is not set as default anymore. All files were created as nobody:nogroup and chown wasn't possible anymore.

Enabling no_root_squash again fixed it:
zfs set sharenfs='rw,no_root_squash' zpool/data

As alternative use /etc/exports/
# sudo nano /etc/exports /zpool/data/ *(rw,no_subtree_check,sync,insecure,no_root_squash)

[aleistah]

Bug-Report
When I perform a backup with ncp-backup, the process is aborted with the following error message:
chown: changing group of '/media/USBdrive/ncp-backups/nextcloud-bkp_20191003_1570136572.tar': Operation not permitted Abort...

By deleting the following line in the ncp-backup script, the backup function works fine again (I don't know why the user group has to be changed for the backup):
chown :www-data "$destfile"

Tried that and found out, that without the chown you get trouble, when restoring.
but u can fix that manually:

1. in case of restoring copy the Backup file to local folder on nextcloudpi
2. "chown :www-data" the backup file before restoring
3. restore the smoothly prepared backup file in nextcloudpi panel

[RayCulp]

Just in case anyone has this problem with a USB drive with FAT, exFAT or NTFS filesystem on it, you need to format the drive with a Linux filesystem, like ext4.

1. Find path of USB stick
   lsblk
   

2. If mounted, unmount it
   sudo umount /mnt/usbstick/ (example)

3. Create filesystem
   sudo mkfs.ext4 /dev/sda1 (example)

4. Mount it
   sudo mount -t auto /dev/sda1 /mnt/usbstick/ (example)

5. Make it permanent
   Get UUID of USB drive
   blkid
   
   Edit fstab file
   sudo nano /etc/fstab
   Add the following line
   UUID=87ad3eff-8894-4c5f-8528-wh4t3v3rth3number15 /mnt/usbstick auto defaults,nofail

[KlausHans]

Stumbled on this issue also. Thx @RayCulp, exFat was the problem in my case.
After sudo mkfs.ext4 /dev/sda1 i would suggest an sudo e2label /dev/sda1 backup to give the partition a descriptive name for the usb automount function. With the automount function of Nextcloudpi you don't need to fiddle with fstab, it gets mounted on /media/backup.