Comment 10 for bug 1776271

I'm also running into this issue on 18.04 (fresh install about 3 months ago)

Motherboard: Asus Sabertooth Z97 Mark S
CPU: Intel I7-4790K
RAM: 32GB
Primary Boot Drive: Crucial M550 256GB SSD
Secondary Drives (ZFS mirror, non-boot): Crucial M550 256GB SSD and Samsung 830 SSD.

sudo apt -f install
...
2 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up grub-efi-amd64-signed (1.93.5+2.02-2ubuntu8.4) ...
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 grub-efi-amd64-signed (--configure):
 installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 1
dpkg: dependency problems prevent configuration of shim-signed:
 shim-signed depends on grub-efi-amd64-signed; however:
  Package grub-efi-amd64-signed is not configured yet.

dpkg: error processing package shim-signed (--configure):
 dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous failure.
                                                                                                          Errors were encountered while processing:
 grub-efi-amd64-signed
 shim-signed
E: Sub-process /usr/bin/dpkg returned an error code (1)

Below is the output requested from cyphermox:

sudo efibootmgr -v

BootCurrent: 0000
Timeout: 1 seconds
No BootOrder is set; firmware will attempt recovery
Boot0003* Hard Drive BBS(HD,,0x0)..GO..NO........O.C.r.u.c.i.a.l._.C.T.2.5.6.M.5.5.0.S.S.D.1.................>..Gd-.;.A..MQ..L. . . . . . . . .4.1.4.2.C.0.0.5.7.B.4.D........BO..NO........O.C.r.u.c.i.a.l._.C.T.2.5.6.M.5.5.0.S.S.D.1.................>..Gd-.;.A..MQ..L. . . . . . . . .4.1.0.2.C.0.1.2.7.B.6.2........BO..NO........O.S.A.M.S.U.N.G. .S.S.D. .8.3.0. .S.e.r.i.e.s.................>..Gd-.;.A..MQ..L.1.S.H.0.E.N.C.A.0.9.3.1.5.6. . . . . . ........BO..NO........O.S.T.2.0.0.0.D.L.0.0.3.-.9.V.T.1.6.6.................>..Gd-.;.A..MQ..L. . . . . . . . . . . . .Y.5.5.D.T.Q.3.X........BO
Boot0084* UEFI OS HD(1,GPT,67596964-080e-41ce-8b5c-42ce19e22bb6,0x800,0x100000)/File(\EFI\BOOT\BOOTX64.EFI)..BO
Boot0085* CD/DVD Drive BBS(CDROM,,0x0)..GO..NO........O.T.S.S.T.c.o.r.p. .D.V.D.-.R.W. .S.H.-.2.1.6.D.B.................>..Gd-.;.A..MQ..L.9.R.J.6.8.6.D.D.0.8.8.1.L.5. . . . . . ........BO..NO........M.H.L.-.D.T.-.S.T.B.D.-.R.E. .B.E.1.4.N.U.4.0.................<..Gd-.;.A..MQ..L.P.R.O.L.I.F.I.C.M.P.0.0.0.0.0.0.1.6.B........BO

sudo efibootmgr -v -c -L ubuntu -l \\EFI\\ubuntu\\shimx64.efi
Could not prepare Boot variable: No such file or directory

Unfortunately, I don't have a BIOS update handy as I'm already on the latest BIOS. I'd really like to reboot my system without down time.