I had python 3.8 and wanted to downgrade it to 3.7, so I purge removed python3.8 and tried to install python3.7 clean
ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: python3 3.8.2-0ubuntu2
ProcVersionSignature: Ubuntu 5.4.0-58.64-generic 5.4.73
Uname: Linux 5.4.0-58-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.14
Architecture: amd64
CasperMD5CheckResult: skip
Date: Mon Jan 4 19:01:37 2021
ErrorMessage: installed python3 package pre-removal script subprocess returned error exit status 127
InstallationDate: Installed on 2020-10-29 (66 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
Python3Details: /usr/bin/python3.8, Python 3.8.5, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: N/A
RelatedPackageVersions:
dpkg 1.19.7ubuntu3
apt 2.0.2ubuntu0.2
SourcePackage: python3-defaults
Title: package python3 3.8.2-0ubuntu2 failed to install/upgrade: installed python3 package pre-removal script subprocess returned error exit status 127
UpgradeStatus: No upgrade log present (probably fresh install)
Thank you for taking the time to report this bug and helping to make Ubuntu better.
Ubuntu tools are designed to work with the default python3 that comes with the system (3.8 for focal/20.04), I don't see what you're describing as an issue with a bug, but instead read it as a user needing support.
I believe a Support site would be more appropriate, eg. https:/