Unable to open Backup Manager in Plesk: no element found: line 1, column 0

Symptoms

• Plesk shows the following error when trying to access Tools & Settings > Backup Manager:

  Error: no element found: line 1, column 0

  ---

  Error: Exec format error in ps utility: command 'ps -p 31663 -o state' was failed

• Plesk administrator may get a similar email message from the Plesk server:

  Server
  Plesk entry point: https://example.com/
  The following error occurred during the scheduled backup process:
  no element found: line 1, column 0

Cause

Corrupted tasks files.

Resolution

1. Connect to the server via SSH.

2. Rename the corrupted task.db file with one of the commands below:

• For RHEL-based OSes:

  # mv /usr/local/psa/PMM/tasks/tasks.db{,.bkp}​

• For Debian-like OSes:

  # mv /opt/psa/PMM/tasks/tasks.db{,.bkp}​