Plesk backup rotation fails: ValueError: time data '1' does not match format '%Y-%m-%d-%H%M%S'

Symptoms

• Backups are not rotated according to the value of Maximum number of full backup files to store and Keep backup files for settings in Tools & Settings > Backup Manager > Schedule or Domains > example.com > Backup Manager > Schedule

• Backup rotation fails with the following error in /usr/local/psa/PMM/logs/pmmcli_daemon.log.<timestamp>:

  CONFIG_TEXT: ValueError: time data '1' does not match format '%Y-%m-%d-%H%M%S'

Cause

This is a Plesk bug with ID #PPPM-10423 which will be fixed in future updates.

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Resolution

As a workaround:

1. Connect to the server via SSH

2. Create folder to back up the log files:

   # mkdir /root/backup-PPPM-10423

3. Back up the log files:

   # cp -a /var/log/plesk/PMM/*.log* /root/backup-PPPM-10423

4. Delete the logs from the original location:

   # rm -rf /var/log/plesk/PMM/*.log*

5. Restart the server to make sure there aren't stuck or zombie processes running