i fail to upgrade to ubuntu 20.04

[livingstone]

Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade.

 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'.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.42
ProcVersionSignature: Ubuntu 4.15.0-135.139-generic 4.15.18
Uname: Linux 4.15.0-135-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.9-0ubuntu7.21
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Fri Jan 22 23:13:52 2021
InstallationDate: Installed on 2018-11-12 (802 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2021-01-22 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

Thanks for taking the time to report this upgrade failure. There is currently a new version of the release upgrader availalbe in -proposed which may resolve the error you've encountered. Please run the following command to test the new version of the upgrader:

  do-release-upgrade -p

Please lets us know the results in this bug report. Thanks again and good luck!

[Launchpad Janitor (janitor)]

[Expired for ubuntu-release-upgrader (Ubuntu) because there has been no activity for 60 days.]