Comment 10 for bug 1242271

> Sorry, I don't understand what you mean here. Do you mean you do have the
grub-efi-amd64 package installed, or you don't have it installed?

Yes, this package installed.

> The Windows bootloader will not boot anything not signed by the Microsoft
key, even if Secure Boot is disabled in the firmware. If your Ubuntu
install has not yet been set up for Secure Boot, you will need to disable
Secure Boot, and manually choose Ubuntu from a firmware boot menu.

My Ubuntu worked fine with Secure Boot in 13.04. But now in 13.10 if I enable secure boot in BIOS, I have Invalid EUFI signature error.

> If you installed grub-efi-amd64, did you also try again to install
shim-signed after that? This should be the last step to enable Secure Boot
on your Ubuntu install.

Yes, this package also installed.