tar: can't create hardlink './upper/etc/uci-defaults/10_migrate-shadow' to './upper/etc/uci-defaults/04_mambafan'

[3245]

it show below error:

./upper/usr/share/terminfo/x/
./upper/usr/share/terminfo/x/xterm-color
./upper/usr/share/terminfo/x/xterm-256color
./upper/usr/share/terminfo/x/xterm
./upper/sbin/
./upper/sbin/parted
./upper/sbin/partprobe
./upper/sbin/block
./upper/root/
./upper/root/exroot.sh
tar: can't create hardlink './upper/etc/uci-defaults/10_migrate-shadow' to './upper/etc/uci-defaults/04_mambafan'
Done ! Your Router Will Be reboot After 5 Seconds ...
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root@OpenWrt:~#

Thanks.