Comment 7 for bug 1776271

I had the same today, dist-upgrade to linux-headers-4.15.0-34 resulted in the same error as above.

sudo apt-get -f install
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  linux-image-4.15.0-32-generic linux-modules-4.15.0-32-generic linux-modules-extra-4.15.0-32-generic
Use 'sudo apt autoremove' to remove them.
0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up shim-signed (1.37~18.04.1+15+1533136590.3beb971-0ubuntu1) ...
Installing for x86_64-efi platform.
Could not prepare Boot variable: No space left on device
grub-install: error: efibootmgr failed to register the boot entry: Input/output error.
dpkg: error processing package shim-signed (--configure):
 installed shim-signed package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 shim-signed
E: Sub-process /usr/bin/dpkg returned an error code (1)

Never had this before and no firmware / BIOS changes. It's a dual-boot system with Win10.

------------------
sudo apt-get -f install
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  linux-image-4.15.0-32-generic linux-modules-4.15.0-32-generic linux-modules-extra-4.15.0-32-generic
Use 'sudo apt autoremove' to remove them.
0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up shim-signed (1.37~18.04.1+15+1533136590.3beb971-0ubuntu1) ...
Installing for x86_64-efi platform.
Could not prepare Boot variable: No space left on device
grub-install: error: efibootmgr failed to register the boot entry: Input/output error.
dpkg: error processing package shim-signed (--configure):
 installed shim-signed package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 shim-signed
E: Sub-process /usr/bin/dpkg returned an error code (1)

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sudo efibootmgr -v -c -L ubuntu -l \\EFI\\ubuntu\\shimx64.efi
Could not prepare Boot variable: No space left on device