[Bug 1898337] [NEW] "Could not calculate the upgrade" error during 18.04 LTS to 20.04 LTS

Public bug reported: Initially the obsolete PPA issue came in first. Sorted that out. And then, came this "Could not calculate the upgrade" issue. Is this something related to the Python version installed? ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: ubuntu-release-upgrader-core 1:18.04.

[Bug 1521035] [NEW] package linux-image-3.19.0-28-generic 3.19.0-28.30~14.04.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

Public bug reported: Failed to install/upgrade: subprocess installed post-installation script returned error exit status 1 ProblemType: Package DistroRelease: Ubuntu 14.04 Package: linux-image-3.19.0-28-generic 3.19.0-28.30~14.04.1 ProcVersionSignature: Ubuntu 3.19.0-33.38~14.04.1-generic 3.19.8-