Various actions fail in Plesk for Linux: Cannot connect to the task manager (plesk-task-manager service might not be running)

Symptoms

• Various actions fail in Plesk with the following error message:

  Cannot connect to the task manager (plesk-task-manager service might not be running): No such file or directory

• One of the following error messages appears in /var/log/plesk/task-manager.log:

  Cannot connect to systemd dbus: dial unix /var/run/dbus/system_bus_socket: connect: connection refused

  ---

  Failed to activate service 'org.freedesktop.systemd1': timed out

  ---

  Config yaml is missing, defaults are used: open /opt/psa/admin/conf/task-manager.yml: no such file or directory
  Detected systemd version is 237
  Cannot connect to systemd dbus: dial unix /var/run/dbus/system_bus_socket: connect: no such file or directory

• plesk-task-manager process may cause high CPU usage.

Cause

The D-Bus service is not running properly.

Resolution

1. Connect to your Plesk server via SSH.

2. Restart the D-Bus service:

   # systemctl restart dbus.socket

3. Verify that only one dbus-daemon service is running in the system:

   3.1. List all dbus services:

   # ps aux | grep dbus-daemon | grep -v grep

   3.2. If there are two or more dbus-daemon services in the output, for example:

   CONFIG_TEXT: message+ 1157 0.9 0.0 9024 6064 ? Ss Mar16 87:50 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
   
   message+ 3341415 0.7 0.0 8160 5364 ? Ss 07:40 0:28 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only

   3.3. Leave the most recent one by killing all older processes using their PID. In the example above, the older process is dated by March 16 and has PID 1157. To kill it, run:

   # kill 1157

4. Restart Plesk Task Manager service:

   # service plesk-task-manager restart