Cannot install necessary packages for Seafile extension: Python version too old

Symptoms

• On a Plesk server installed on the AlmaLinux 8 operating system, when going to Extensions > My Extensions > Seafile > Open the following warning is shown:

  PLESK_WARN: Necessary packages are not installed.

• When pressing the Install button next to the warning the installation fails with the following error:

  PLESK_ERROR: Python version too old.

• The Seafile extension has been installed, but has not been started yet

• The Installed Python package on the server is python3X, with X being lower than 9:

  # root @ server in ~: yum list installed | grep python3
  ...
  python36.x86_64 3.6.8-39.module_el8.10.0+3769+3838165b @appstream
  python36-devel.x86_64 3.6.8-39.module_el8.10.0+3769+3838165b @appstream

Cause

The currently installed Python package (python3X) is a lower version than Python 3.9.

Seafile requires at least Python 3.9 but does not install the python39 packages, so it fails to set Python version as 3.9 since that version is absent from the server.

Resolution

Until the issue is fixed in a next update of the Seafile extension, you can use the following workaround:

1. Connect to the server via SSH.

2. Install the necessary python39-lxml package:

   # yum install python39-lxml