grub-install: error: failed to register the EFI boot entry: Function not implemented

Question

after upgrading to Ubuntu 19.04 I frequently got a 'failed to register the EFI boot entry: Function not implemented.' error when installing new packages. Now I updated to Ubuntu 19.10 and the installation first aborted because of my system being 'unstable'. After executing 'apt-get upgrade' the next time the system upgraded anyway.

Now when I run 'sudo apt-get upgrade' I get:

[...]

Do you want to continue? [Y/n] y
Setting up grub-efi-amd64-signed (1.128+2.04-1ubuntu12) ...
Installing for x86_64-efi platform.
grub-install: warning: efivarfs_get_variable: open(/sys/firmware/efi/efivars/blk0-47c7b225-c42a-11d2-8e57-00a0c969723b): No such file or directory.
grub-install: warning: efi_get_variable: ops->get_variable failed: No such file or directory.
grub-install: warning: device_get: readlink of /sys/block/nvme0n1/device/driver failed: No such file or directory.
grub-install: warning: is_gpt_valid: GUID Partition Table Header signature is wrong: 0 != 5452415020494645: Invalid argument.
grub-install: warning: is_gpt_valid: GUID Partition Table Header signature is wrong: 0 != 5452415020494645: Invalid argument.
grub-install: warning: msdos_disk_get_extended_partition_info: extended partition info is not supported: Function not implemented.
grub-install: warning: msdos_disk_get_partition_info: could not get extended partition info: Function not implemented.
grub-install: warning: get_partition_info: neither MBR nor GPT is valid: Function not implemented.
grub-install: warning: make_hd_dn: could not get partition info: Function not implemented.
grub-install: warning: efi_va_generate_file_device_path_from_esp: could not make HD() DP node: Function not implemented.
grub-install: warning: efi_generate_file_device_path_from_esp: could not generate File DP from ESP: Function not implemented.
grub-install: error: failed to register the EFI boot entry: Function not implemented.
dpkg: error processing package grub-efi-amd64-signed (--configure):
 installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 grub-efi-amd64-signed
E: Sub-process /usr/bin/dpkg returned an error code (1)

So now some additional warnings appear. I can use my system with no apparent restrictions but after reading during the 19.10 upgrade that my system may be unstable I want to check how to fix this issue.

Would be great if someone knows a solution.

Answer 1

I've had this same issue, and unfortunately can only help you with a temporary solution. Perhaps somebody else can later add a definite solution. In my case I could anticipate this by:

1. After your update, keep your terminal window open. If you didn't use your command line for updating, open terminal (CTRL+ALT+T).
2. Now open your Partition Manager (e.g. GParted).
3. In GParted, unmount your EFI System Partition (/efi/boot)
4. Go back to your terminal, and type sudo apt install -f followed by an Enter
5. When this has finished, go back to GParted and mount your EFI System Partition (/efi/boot)
6. If you now do sudo apt update && sudo apt upgrade in terminal (again), your errors should be gone.