package linux-image-4.15.0-20-generic 4.15.0-20.21 failed to install/upgrade: run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 127

a plain 17-10 to 18.04 distribution upgrade gave this

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-20-generic 4.15.0-20.21
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic i686
NonfreeKernelModules: wl
ApportVersion: 2.20.9-0ubuntu7
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: cp 1600 F.... pulseaudio
Date: Mon May 7 18:47:07 2018
ErrorMessage: run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 127
InstallationDate: Installed on 2017-08-28 (252 days ago)
InstallationMedia: Ubuntu-MATE 17.04 "Zesty Zapus" - Release i386 (20170412)
MachineType: Dell Inc. Studio 1737
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-20-generic root=UUID=3b44acaa-ce70-4d0f-89cd-b1dc78f53a0e ro quiet splash vt.handoff=1
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3
PythonDetails: /usr/bin/python2.7, Python 2.7.15rc1, python-minimal, 2.7.15~rc1-1
RelatedPackageVersions: grub-pc 2.02-2ubuntu8
SourcePackage: initramfs-tools
Title: package linux-image-4.15.0-20-generic 4.15.0-20.21 failed to install/upgrade: run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 127
UpgradeStatus: Upgraded to bionic on 2018-05-07 (0 days ago)
dmi.bios.date: 10/09/2008
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A01
dmi.board.name: 0P792H
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A01
dmi.modalias: dmi:bvnDellInc.:bvrA01:bd10/09/2008:svnDellInc.:pnStudio1737:pvrA01:rvnDellInc.:rn0P792H:rvrA01:cvnDellInc.:ct8:cvrA01:
dmi.product.name: Studio 1737
dmi.product.version: A01
dmi.sys.vendor: Dell Inc.