package initramfs-tools 0.136ubuntu6.7 failed to install/upgrade: installed initramfs-tools package post-installation script subprocess returned error exit status 1

[Mikkel Kirkgaard Nielsen]

Upgrading from 18.04 to 20.04.

No space left on /boot.
Solved by changing compression from lz4 to xz and regenerating before reboot.

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: initramfs-tools 0.136ubuntu6.7
ProcVersionSignature: Ubuntu 5.4.0-147.164-generic 5.4.231
Uname: Linux 5.4.0-147-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.26
Architecture: amd64
CasperMD5CheckResult: skip
Date: Fri Apr 21 00:16:53 2023
ErrorMessage: installed initramfs-tools package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2016-03-02 (2605 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
PackageArchitecture: all
Python3Details: /usr/bin/python3.8, Python 3.8.10, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: /usr/bin/python2.7, Python 2.7.18, python-is-python2, 2.7.17-4
RelatedPackageVersions:
 dpkg 1.19.7ubuntu3.2
 apt 2.0.9
SourcePackage: initramfs-tools
Title: package initramfs-tools 0.136ubuntu6.7 failed to install/upgrade: installed initramfs-tools package post-installation script subprocess returned error exit status 1
UpgradeStatus: Upgraded to focal on 2023-04-20 (0 days ago)

[Mikkel Kirkgaard Nielsen (mikini)]

The issue I experienced here, with ~0 bytes free on /boot, produces a more clear "no space left" error than other initramfs-tools post-installation bugs.

See Df.txt;
/dev/sda1 238924 232193 0 100% /boot

See end of DpkgTerminalLog.txt;
update-initramfs: Generating /boot/initrd.img-5.4.0-147-generic
cat: write error: No space left on device
update-initramfs: failed for /boot/initrd.img-5.4.0-147-generic with 1.
dpkg: error processing package initramfs-tools (--configure):
 installed initramfs-tools package post-installation script subprocess returned error exit status 1