RB750r2 sysupgrade cant unmount Resource busy error

Username: Francis

Origin: https://bugs.openwrt.org/index.php?do=details&task_id=741

Mikrotik RB750r2 (hEX lite)

Reboot (SNAPSHOT, r4049-9412fc29) The snapshot build dated 28/04/2017 (Europe timezone)

I first did a boot up on TFTP with

mikrotik-rb-nor-flash-16M-initramfs-kernel.bin

and then downloaded the

lede-ar71xx-mikrotik-rb-nor-flash-16M-squashfs-sysupgrade.bin

via wget into cd /tmp

Then i did sysupgrade lede-ar71xx-mikrotik-rb-nor-flash-16M-squashfs-sysupgrade.bin however everything seems to be installed ok but got theses following errors?

root@LEDE:/tmp# sysupgrade lede-ar71xx-mikrotik-rb-nor-flash-16M-squashfs-sysupgrade.bin

Cannot save config while running from ramdisk.

killall: watchdog: no process killed

Unlocking firmware ...

Erasing firmware ...

Sending TERM to remaining processes ... udhcpc odhcp6c ntpd dnsmasq ubusd askfirst logd netifd odhcpd

Sending KILL to remaining processes ... askfirst

Performing system upgrade...

Unlocking firmware ..

Writing from to firmware ...

Appending jffs2 data from /tmp/sysupgrade.tgz to firmware..

.File /tmp/sysupgrade.tgz does not exist

Upgrade completed

Rebooting system...

umount: can’t unmount /dev/pts: Resource busy

umount: can’t unmount /dev: Resource busy

umount: can’t unmount /tmp: Resource busy

umount: can’t unmount /: Invalid argument