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

[Stewart Sutton]

None - see summary.

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: initramfs-tools 0.136ubuntu6
ProcVersionSignature: Ubuntu 5.4.0-37.41-generic 5.4.41
Uname: Linux 5.4.0-37-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.2
Architecture: amd64
CasperMD5CheckResult: skip
Date: Sat Jun 13 14:09:12 2020
ErrorMessage: installed initramfs-tools package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2020-06-13 (0 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
PackageArchitecture: all
Python3Details: /usr/bin/python3.8, Python 3.8.2, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: N/A
RelatedPackageVersions:
 dpkg 1.19.7ubuntu3
 apt 2.0.2ubuntu0.1
SourcePackage: initramfs-tools
Title: package initramfs-tools 0.136ubuntu6 failed to install/upgrade: installed initramfs-tools package post-installation script subprocess returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Mikkel Kirkgaard Nielsen (mikini)]

This one is different from other initramfs-tools post-installation errors. /boot is on / which has plenty of space, but update-initramfs is missing /boot/initrd.img-5.4.0-37-generic.new.

See Df.txt;
/dev/sda5 436953712 8324136 406363876 3% /
/dev/sda1 523248 4 523244 1% /boot/efi

See end of DpkgTerminalLog.txt;
update-initramfs: Generating /boot/initrd.img-5.4.0-37-generic
mv: cannot stat '/boot/initrd.img-5.4.0-37-generic.new': No such file or directory
dpkg: error processing package initramfs-tools (--configure):
 installed initramfs-tools package post-installation script subprocess returned error exit status 1