Plesk provides error in Tools & Settings > IP Addresses Banning (Fail2Ban) > Banned IP Addresses menu: No module named 'fail2ban'

Symptoms

• Error like below appears during an attempt to access Tools & Settings > IP Address Banning (Fail2Ban) > Banned IP Addresses menu:

  PLESK_ERROR: f2bmng failed: Traceback (most recent call last): File "/usr/bin/fail2ban-client", line 34, in <module> from fail2ban.client.fail2banclient import exec_command_line, sys ModuleNotFoundError: No module named 'fail2ban' ERROR:__main__:Command '['/usr/bin/fail2ban-client', '--str2sec', '1w']' returned non-zero exit status 1. ERROR:__main__:Not a time string: 1w

• Server uses Python 3.9 (or some other version):

  # /usr/bin/python3 -V
  Python 3.9.0

Cause

Fail2Ban component requires Python 3.6 version, but the server invokes another Python version. Such behavior is considered as a bug with ID PPPM-14555.

Resolution

Workaround: modify the Fail2Ban files, so it would use Python 3.6

1. Log into server via SSH.

2. Modify the first line of the /usr/bin/fail2ban-client file using one of the following methods:

• Open file using vi (or some other editor), and specify Python 3.6 on the first line:

  #!/usr/bin/python3.6
  

Or

• Run the following command to modify the file:

  # sed -i '1s|^#!/usr/bin/python3|#!/usr/libexec/platform-python3.6|' /usr/bin/fail2ban-client