Recovering from a failed update

strong textI have been running a stable installation of 18.04.02 Desktop for about 30 months. The server wasn't powered on for about 2 weeks so when powered on this morning it went through its automatic security updates. After they had finished I ran the update manager and got these error messages

Evidently the packages are inconsistent. I have checked by running "sudo nano /etc/apt /sources.list" that I haven't got any third party repositories. At least I think so.

Is there anyway I can revert to a consistent set of packages. No I do not have a recent backup. I have of course followed the suggestions in the error message

EDITED in response to comment. Output from apt-get install -f

Your Hardware Enablement Stack (HWE) is supported until April 2023.
Last login: Mon Sep 27 15:38:50 2021 from 192.168.1.96
stephen@leia:~$
stephen@leia:~$ sudo apt-get install -f
[sudo] password for stephen:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following package was automatically installed and is no longer required:
  linux-hwe-5.4-headers-5.4.0-77
Use 'sudo apt autoremove' to remove it.
The following additional packages will be installed:
  libwebkit2gtk-4.0-37
Suggested packages:
  libwebkit2gtk-4.0-37-gtk2
The following packages will be upgraded:
  libwebkit2gtk-4.0-37
1 to upgrade, 0 to newly install, 0 to remove and 24 not to upgrade.
1 not fully installed or removed.
Need to get 0 B/13.4 MB of archives.
After this operation, 81.9 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
(Reading database ... 264170 files and directories currently installed.)
Preparing to unpack .../libwebkit2gtk-4.0-37_2.32.4-0ubuntu0.18.04.1_amd64.deb ...
Unpacking libwebkit2gtk-4.0-37:amd64 (2.32.4-0ubuntu0.18.04.1) over (2.32.3-0ubuntu0.18.04.1) ...
dpkg-deb (subprocess): decompressing archive member: lzma error: compressed data is corrupt
dpkg-deb: error: <decompress> subprocess returned error exit status 2
dpkg: error processing archive /var/cache/apt/archives/libwebkit2gtk-4.0-37_2.32.4-0ubuntu0.18.04.1_amd64.deb (--unpack):
 cannot copy extracted data for './usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37.53.5' to '/usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37.53.5.dpkg-new': unexpected end of file or stream
Errors were encountered while processing:
 /var/cache/apt/archives/libwebkit2gtk-4.0-37_2.32.4-0ubuntu0.18.04.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
stephen@leia:~$

The machine appears to be stable but now cannot updated. Is it a hopeless cause?

Thanks for any help

Your output has the information you need to solve the problem:

cannot copy extracted data for './usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37.53.5' to '/usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37.53.5.dpkg-new':unexpected end of file or stream

Let's abstract that a little for easier understanding...

cannot copy extracted data for X to Y:unexpected end of file or stream

X = './usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37.53.5'
Y = '/usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37.53.5.dpkg-new'

What does it mean?

"unexpected end of file or stream" means exactly what it says - the package is incomplete or corrupt. You must trash it from your local cache and let apt download a new, fresh, complete copy of the package.

Which package?

Let's ask apt that question, using the path provided by X:

• The package name is on the second line: libwebkit2gtk-4.0-37

$ dpkg -S /usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37
libwebkit2gtk-4.0-37:amd64: /usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37

How do I delete the corrupt local package and download a fresh new copy?

$ sudo apt clean libwebkit2gtk-4.0-37                 // Delete local
$ sudo apt update
$ sudo apt install --reinstall libwebkit2gtk-4.0-37   // Download fresh

The solution that worked for me was executing sudo apt full-upgrade which had the effect of downloading the fresh copy of the corrupted package followed by sudo apt upgrade