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I followed the procedure mentioned at Installing Ubuntu on a Pre-Installed Windows 8 (64-bit) System (UEFI Supported) on toshiba satellite laptop.

also tried the boot-repair and logs @

Its not booting to windows as well as ubuntu. It goes to grub command prompt.

When on initial screen it briefly shows error message as failed to open /efi/Microsoft/boot/grubx64.

Please advise.

EDIT : Secure boot in on and boot mode is UEFI Boot

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Do you have secure boot on? It does look like you have the signed kernels installed so it should boot with secure boot on or off. Not sure if shim gets renamed to grubx64, but you should be booting shim if in secure boot mode. – oldfred Oct 30 '13 at 3:24
Bug 1091464 may prevent you from booting Windows from grub. If so, use the efi menu to select harddisk then Windows. My Toshiba S855 -5378 never needed to rename any bootloaders either. – ubfan1 Oct 30 '13 at 4:59

The error message refers to /efi/Microsoft/Boot/grub64.efi (I presume there was a efi after the dot there, although your message didn't say so.) This implies that shim is installed in /efi/Microsoft/Boot, presumably as bootmgfw.efi, and is being launched; however, your Boot Repair output shows no evidence of grubx64.efi being present there, as it must be. (Shim is hard-coded to launch grubx64.efi from the same directory in which it resides.)

This suggests an easy solution: Copy grubx64.efi from /efi/ubuntu to /efi/Microsoft/boot. You'll need to use an emergency disc and mount /dev/sda2 somewhere convenient to do this copy, of course.

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