Updating to the latest grub version leads to “error: symbol ‘grub_efi_find_last_device_path’ not found” on my dual boot system having Ubuntu 15.10 next to Windows 10.
This can be fixed by downgrading to the version before the latest one in the ubuntu repository till this bug is fixed.
Here is how I downgraded my grub installation:
sudo apt-get install grub2-common=2.02~beta2-29ubuntu0.2 \ grub-common=2.02~beta2-29ubuntu0.2 grub-efi-amd64=2.02~beta2-29ubuntu0.2 \ grub-efi-amd64-bin=2.02~beta2-29ubuntu0.2 sudo apt-mark hold grub-common grub-efi-amd64-bin grub2-common grub-efi-amd64
Without the hold line apt would install the latest version on the next upgrade. As soon as the bug is fixed you can remove the hold mark with
sudo apt-mark install grub-common grub-efi-amd64-bin grub2-common grub-efi-amd64