Can't boot on Win 8 after installing Ubuntu : "A required device isn’t connected or can’t be accessed"

I have a lot of troubles setting up a dual boot on my new computer.

After I set up and wired up the hardware I installed W8 as I guessed it would be harder to install with Ubuntu already installed.

I created 2 partitions 15GB for Ubuntu and 95GB for W8.

Then I installed Ubuntu 14.04, carrebully following the dual boot installation guide from french Ubuntu site

Grub was showing up with 5 entries, Ubuntu, Memory test x2, W8 loader, W8 recovery. I'm able to boot smoothly on Ubuntu but not on W8 : I get a "A required device isn’t connected or can’t be accessed." error.

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I googled a lot of stuff and tried differents ways to fix it but I still can't make it :(

• I ran boot-repair (here's the report)
• I disabled FastBoot / SecureBoot in my BIOS
• I changed my BIOS to Legacy mode
• I tried to repair W8 with Windows Recovery tools : nothing working, I can't even start the repair process
• I ran chkdsk, it reported no error

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Other informations that might help :

• os-prober returns / detects nothing
• os detection from Windows Recovery tools detects nothing
• • not 100% sure : I might forgot to turn off W8 hibernate feature before installing Ubuntu
• Here are my full hardware details

1 Answer

Your configuration is strange, and that strangeness may hide a problem. You have:

• Two hard disks (no problem there).
• It appears that /dev/sdc is a Windows installation disk that you haven't unplugged. This also is not a real problem.
• /dev/sda is partitioned with MBR and seems to hold Windows. This implies that Windows is booting in BIOS/CSM/legacy mode; however, the MBR of the disk holds SYSLINUX, not the Windows boot loader.
• /dev/sdb is partitioned using GPT and seems to hold Ubuntu. It has a BIOS Boot Partition, which also implies a BIOS-mode installation of Ubuntu.

Although it's legal to mix MBR and GPT, and to use GPT on a disk that boots Linux in EFI mode, this setup is unconventional. The fact that SYSLINUX is on the MBR of /dev/sda may be an issue, although IIRC, SYSLINUX can chainload to a Windows boot loader located elsewhere.

It's possible that your Windows recovery tools are being thrown by the GPT /dev/sdb. If so, unplugging it and attempting a recovery may work. You could also try asking about this on a Windows forum, since the Windows boot failure is basically a Windows issue. (Although the presence of SYSLINUX might be part of the problem, the solution if this is the case will be to re-install the Windows boot loader on /dev/sda, which is a Windows-specific solution.)

If you can't get that to work, you could switch your approach radically and re-install both Windows and Ubuntu in EFI mode: Disable the Compatibility Support Module (CSM) in the firmware, wipe both disks clean, and re-install both OSes. (It is possible to convert both from BIOS-mode to EFI-mode booting, but that will likely take more effort than re-installing.) See my page on the subject for why the CSM can create problems. I don't think the CSM is fundamentally the issue for you, but switching to an EFI-mode boot will likely bypass whatever the issue actually is, so it's worth trying if you can't find another solution.