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When I do a backup in TWRP on my Honor 8 (FRD-L09), it invariably end with a message saying that it failed to unmount /system due to device or resource being busy. The header still says that the backup is complete, and that it was successful.

In case it makes a difference, I'm running FRD-L09C432B131, which is EMUI 4.1, Android 6.0. Kernel is 3.10.94 from 11 October 2016. This is what was installed on the phone when I got it. I got the bootloader unlock code from Huawei, by registering and applying for it. TWRP is 3.0.2-0 downloaded from here and flashed using fastboot on Windows 10.

Here's a photo of TWRP after finishing the backup:

enter image description here

Need I worry about this?

  • Can you boot properly after this? If yes, no worries. – Andy Yan Feb 4 '17 at 4:27
  • To be more sure, reboot into recovery again and see if this warning persists (it shouldn't). – Andy Yan Feb 4 '17 at 4:39
  • @AndyYan I'll try that later. Right now I'm off to bed. Thanks again. – Duane Dibbley Feb 4 '17 at 4:41
  • @AndyYan I just tested. Did a backup. Then I tried to manually unmount /system, both from the TWRP menu and from its built-in terminal. Both failed with the same message. Then I rebooted, selecting Recovery from TWRP's menu. When it came back up, /system had not been mounted, and no error/warning messages appeared. And rebooting the system after this works normally. – Duane Dibbley Feb 6 '17 at 17:49
  • It's quite obvious that the recovery itself is buggy. Not unexpected for Kirin devices... I'll post the above as an answer. – Andy Yan Feb 6 '17 at 23:44
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To isolate the problem, 1) reboot into Android and see if it does so properly, and 2) reboot back into recovery and do the same operations.

Judging from your response on the 2 points, it seems your recovery is at fault here. Not unmounting /system is usually not a problem: that step is done as a safety precaution to prevent accidental modification to /system when not flashing. As long as you don't do that yourself you should be fine.

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