Email notification is sent to Plesk administrator during Plesk backup creation: Unable to find archive metadata

Symptoms

• In an attempt to create a backup of the example.com subscription the message below is sent to the Plesk administrator:

  Domain: example.com Plesk
  Entry point: https://hostname.com:8443/
  The following error occurred during the scheduled backup process: pmm-ras failed (Error code = 1): Repository error: Failed to read backup backup_example.com_XX_XX.tar: Import error: Unable to find archive metadata. The archive is not valid Plesk backup or has been created in an unsupported Plesk version

• The following error message can be found in the /var/log/plesk/PMM/backup-XX_XX/backup.log file:

  Unable to find base backup for creation of incremental one, the full backup will be created. Error: Failed to exec pmm-ras: Exit code: 119: Import error: Unable to find archive metadata. The archive is not valid Plesk backup or has been created in an unsupported Plesk version.

Cause

Remote FTP storage does not support TLS of 1.3 version which is used by default by Plesk Backup, e.g:

• For TLS 1.2 - the data regarding TLSv1.2 support is returned:

  # openssl s_client -connect remotehost.com:21 -tls1_2
  CONNECTED(00000003)
  ...
  Verification: OK
  ...
  SSL-Session:
  Protocol : TLSv1.2

• For TLSv1.3 - no data regarding the TLS version is returned:

  # openssl s_client -connect remotehost.com:21 -tls1_3
  CONNECTED(00000003)
  ...
  Verification: OK

  Note: to check TLSv1.3 on a remote FTP storage OpenSSL should be v1.1.1 or newer.

Resolution

1. Log into Plesk.

2. Go to Extensions > My Extensions > Panel.ini Editor > Open > Editor.

   Note: in case the Panel.ini Editor extension is missing, install it using this article.

3. Add the line below under the [pmm] section:

   • In case the remote FTP storage supports TLS of 1.2 version:

     ftpMaxTlsVersion = 12

   • In case the remote FTP storage supports TLS of 1.1 version:

     ftpMaxTlsVersion = 11

4. Scroll down and press the Save button.