Windows 10 - Ubuntu 15.10 dual: No Ubuntu after W10 shutdown, not restart
Problem:
If I do restart Win10 and start Ubuntu (instead of W10) the Grub starts Ubuntu 15.10 without issues.
If I shutdown Windows 10 instaed, Ubuntu does not boot. Grub starts, then total failure. No visible reason.
I can reproduce it as often as I like.
Starting Windows 10 after that incident is fine!
Starting Ubuntu does NOT work at all....
EXCEPT I shut down Windows-10 with a RESTART.
Problem:
Windows 10 - Ubuntu 15.10 dual boot gets f***ed up by Windows 10. No Ubuntu after W10 shutdown.
Why??
SOLUTION / The answer is: The Windows 10 shutdown is NO shutdown. It is a hibernation state. The boot sector gets poisoned by Windows-10 after entering the Hibernation state and shutting down the hardware.
So Grub / Ubuntu can not handle it, the boot sect is malformed.
Solution:
Go to Windows 10 settings and disable the Fast Boot option in the Energy settings.
In German it is "Schnellstart aktivieren (empfohlen)". NO NOT CHECK!!! This option kills Ubuntu boot!
Sie finden diese Einstellung in Windows-10 Energieoptionen / Systemeinstellungen / Einstellungen fuer das Herunterfahren als ersten Punkt.
Then it works fine.
Applies to earlier Windows 8 and 7 too.
You see the answer is in line.
And the right term will help you: HIBERNATION.
There is a CLI in Wondows 7 / 8 / 10 helping you.
Press "Windows" + R, choose to run CMD as admin (!!). Then At the command prompt, type powercfg.exe /hibernate off, and then press Enter.
This does NOT work with some vendor customised Win versions. Good luck ;-) then.
Disabled HIBERNATION will re-enable Ubuntu boot.
This applies too when the Winstuff fell asleep. Depending on your settings it will go to hibernation without your interaction.
Then the same applies but you better wake up Windows and boot a true operating system before re-configuring anything.
FF!!