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Unable to create a Plesk scheduled backup to a remote FTP storage: Curl error: Unable to resume an interrupted download: (28) Timeout was reached

Daniel Yordanov
Updated
kb: bug Plesk for Linux

Applicable to:

  • Plesk for Linux

Symptoms

  • In an attempt to create a Plesk scheduled backup to a remote FTP server the process fails with the error:

    PLESK_ERROR: pmm-ras failed (Error code = 1):
    STDOUT: Curl error: Unable to resume an interrupted download: (28) Timeout was reached: Last FTP request: PASS *****: Last FTP response: 421 I can't accept more than 3 connections as the same user: Connection to the FTP server has lost

  • The similar or the following error can be found in usr/local/psa/PMM/logs/backup-XX/backup.log file:

    CONFIG_TEXT: Curl error: (21) Quote command returned error: Last FTP request: QUIT Last FTP response: 221 Goodbye [common/plesk-utils/PMM/repository-transport/transport.cpp:1010] virtual void plesk::tRepositoryFtp::Delete(const string&) INFO: pmm-ras finished. Exit code: 126

  • The following errors can be found in /var/log/plesk/PMM/backup-XX/pmmcli.log and /var/log/plesk/PMM/pmmcli.log files:

    CONFIG_TEXT: [type 'exceptions.TypeError'] cannot concatenate 'str' and 'list' objects
    TypeError: cannot concatenate 'str' and 'list' objects
    [error][module]pmmcli[/module][operation]<type 'exceptions.TypeError'>[/operation][message]cannot concatenate 'str' and 'list' objects at File "/usr/local/psa/admin/sbin/pmmcli", line 6, in <module>

Cause

This is a Plesk bug with the ID #PPPM-8749, which has been resolved permanently in Plesk Obsidian version 18.0.57.

Resolution

Update Plesk Obsidian to the latest available version by using the information in this article:

How to update Plesk Obsidian to the latest build

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Comments

2 comments
Date Votes
  • Avatar
    Unknown User

    Seems a similar Bug has be reintroduced in current latest release Plesk Obsidian Version 18.0.53
    Sad fact: In this "issue" of the bug the workaround mentioned by editing the panel.ini does not work anymore :-/
    Please fix - by now no backup is possible on any updated instances (other servers that are still on 18.0.53 Update 3 don't face that problem).

    0
  • Avatar
    MEREL Tanguy

    It seems like this error is back. 

    Since Plesk Obsidian 18.0.68 Update 2 has been installed (April 8th, 2025), we get this error for every single backup, on two different hosts. 

    Plesk entry point: https://******:8443/

    The following errors occurred during the scheduled backup process:

    Transport error: unable to read file /check4/test: Curl error: Unable to resume an interrupted download: (28) Timeout was reached: The last FTP request: PASS *****: The last FTP response: 421 I can't accept more than 3 connections as the same user: Connection to the FTP server has lost
     

    1

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