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

Symptoms

• On a Plesk for Linux server, the following error is shown on attempt to open the menu 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

  ---

  Error: database disk image is malformed

• Plesk administrator may get a similar email notification:

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

Cause

The file with Plesk backup tasks is corrupted.

Resolution

1. Connect to the server using SSH.

2. Rename the corrupted file tasks.db:

• On AlmaLinux/CentOS/RHEL/CloudLinux/Rocky Linux:

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

• On Ubuntu and Debian:

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