Plesk fails to update to version 18.0.42 or newer fails: Failed to solve dependencies: package requires python3

Symptoms

• Plesk fails to update to the version 18.0.42 or newer because it requires python3 and python3-libs packages:

  Exception: Failed to solve dependencies:
  plesk-service-node-utilities-18.0-2.centos.7+p18.0.42.0+t220221.1008.x86_64 requires python3-libs
  plesk-service-node-utilities-18.0-2.centos.7+p18.0.42.0+t220221.1008.x86_64 requires python3
  plesk-core-utilities-18.0-2.centos.7+p18.0.42.0+t220218.1310.x86_64 requires python3-libs
  plesk-core-utilities-18.0-2.centos.7+p18.0.42.0+t220218.1310.x86_64 requires python3
  alt-python36-3.6.8-1.el7.x86_64 requires alt-python36-libs(x86-64) = 3.6.8-1.el7
  plesk-python3-regex-2021.11.10-2.centos.7+p18.0.42.0+t220121.1925.x86_64 requires python3

  ERROR: The Yum utility failed to install the required packages.
  Attention! Your software might be inoperable.
  Visit https://support.plesk.com/ to search for a solution.
  exit status 1

• Both packages python3 and python3-libs are not found in the repository list, e.g.:

  # yum whatprovides python3
  Loaded plugins: fastestmirror, vzlinux
  ...
  No matches found

Cause

Repositories with python3 and python3-libs packages are disabled.

Resolution

1. Connect to the server via SSH.

2. Check the repositories in /etc/yum.repos.d and find the disabled ones, for example:

   # grep -i "enabled" /etc/yum.repos.d/* | grep 0
   /etc/yum.repos.d/centos-7-x86_64.repo:enabled=0

   Note: The packages python3 and python3-libs are usually provided by the vendors Base repo, e.g. /etc/yum.repos.d/CentOS-Base.repo

3. Edit the repository file found in step 2 - change the value for "enable" to "1" or remove the line "enabled=0" from the file.

4. Proceed with updating Plesk.