no update from xubuntu 16.04

[Roberto Nocci]

Calculating the changes

Calculating the changes

Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade.

This was caused by:
* Upgrading to a pre-release version of Ubuntu
This is most likely a transient problem,
please try again later.
If none of this applies, then please report this bug using the
command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal. If
you want to investigate this yourself the log files in
'/var/log/dist-upgrade' will contain details about the upgrade.
Specifically, look at 'main.log' and 'apt.log'.

Restoring original system state

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.44
ProcVersionSignature: Ubuntu 4.15.0-74.84-lowlatency 4.15.18
Uname: Linux 4.15.0-74-lowlatency x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.9-0ubuntu7.24
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: XFCE
Date: Fri Aug 6 07:28:05 2021
InstallationDate: Installed on 2018-01-31 (1282 days ago)
InstallationMedia: Xubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2021-08-06 (0 days ago)

[Chris Guiver (guiverc)]

Thank you for taking the time to report this issue and helping to make Ubuntu better.

You have 3rd party packages that are the issue, eg.

Broken kxstudio-meta-audio-plugins:amd64 Depends on qsampler:amd64 < 2:0.4.2-1kxstudio1v5 @ii mR >
  Considering qsampler:amd64 260 as a solution to kxstudio-meta-audio-plugins:amd64 0
  Removing kxstudio-meta-audio-plugins:amd64 rather than change qsampler:amd64

kxstudio-meta-audio-plugins is a 3rd party package, and has dependencies that do not allow upgrade to occur. Please also note this may not be your only 3rd party package blocking upgrade.

Unofficial software packages not provided by Ubuntu can be removed using a 'ppa-purge' tool prior to upgrade.