Incomplete library necessary for upgrade.

[Mauro Posarelli]

Good morning,
I tryed to upgrade from lubuntu 16.4 to 18 version. The download is started well, but when the system need to install the upgrade, there is the answer that some parts are absent.
I am not expert, and I ask with regard if someone can indicate were I can download the complete package for upgrade.
Thanks a lot.
Mauro

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.29
ProcVersionSignature: Ubuntu 4.4.0-177.207-powerpc-smp 4.4.214
Uname: Linux 4.4.0-177-powerpc-smp ppc
ApportVersion: 2.20.1-0ubuntu2.23
Architecture: powerpc
CrashDB: ubuntu
Date: Mon Apr 13 17:42:46 2020
InstallationDate: Installed on 2017-02-13 (1155 days ago)
InstallationMedia: Lubuntu 16.04 LTS "Xenial Xerus" - Release powerpc (20160420.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to xenial on 2020-04-13 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2020-04-13 17:39:04.699289
 Log time: 2020-04-13 17:39:25.460155
 Log time: 2020-04-13 17:42:33.476698
 Log time: 2020-04-13 17:44:36.667602
VarLogDistupgradeTermlog:

mtime.conffile..etc.update-manager.release-upgrades: 2020-04-10T16:49:33.264738