Systemctl fails to start service: Too many levels of symbolic links

Symptoms

• Plesk is running on CentOS 7.7

• There are multiple failed services:

  # systemctl list-units –failed
  UNIT LOAD ACTIVE SUB DESCRIPTION
  ● courier-authdaemon.service loaded active failed Courier-IMAP authentication daemon
  ● courier-imapd.service loaded active failed Courier IMAP server
  ● courier-imaps.service loaded active failed Courier IMAP server with SSL/TLS support
  ● courier-pop3d.service loaded active failed Courier POP3 server
  ● courier-pop3s.service loaded active failed Courier POP3 server with SSL/TLS support
  ● spamassassin.service loaded active failed Spamassassin daemon
  ● systemd-sysctl.service loaded failed failed Apply Kernel Variables
  ● systemd-tmpfiles-setup-dev.service loaded failed failed Create Static Device Nodes in /dev
  ● systemd-vconsole-setup.service loaded failed failed Setup Virtual Console

• Systemctl cannot…