Here, we have been voting for nothing. Plesk hasn't added that feature before because they wanna sell the backup plugin and make more money. It's not fair. I know guys you won't implement that feature. Maybe 2 years later, maybe 5 years?

You can add:

[pmm]
ftpMaxResumeAttempts = 10
ftpMaxResumeFailures = 30

To the panel.ini, solved the problem for me.

@Plesk Staff: The problem as we observe it quite frequently: The FTP upload fails for unknown reasons when run as a daily backup job. Thus, the backup is stored locally and consumes storage space on the server.

In order to ensure that the FTP server has a backup of every day, the current situation means that you manually have to trigger the backup on the same day so that there is another backup on the FTP storage. Once this has been done successfully, you can then delete the local backup.

If you had the opportunity to just move the local backup to the FTP storage, this would speed up the process and require less admin action. Ideally, you could even define how many times the server should try to upload the backup to the FTP storage. In addition, it could help if local backups would be stored as one single archive file (which I can easily move to the FTP storage), instead of having multiple files and directories for one backup task.

Interestingly, the manually triggered backup so far always succeeded with uploading while the automated one fails on a regular basis. (Thus, it would be interesting to find out if there is some kind of bug in the automated backup scripts.)

"Plesk StaffAdminPlesk Staff (Admin, Plesk) responded · Jun 8, 2016

If there is uploading error, you need to fix the reason and then start upload process again. ..." HOW COULD I DO THAT? Where is these button?

Sometimes our 60GB ftp server backup at sunday 05.00 o'clock breaks. So the backup is stored local.
Now is missing the function to retry the upload to the ftp space. The whole backup process must be done new.
This makes no sense because the backup is ok, only the location is wrong.
I miss the button "load this backup to FTP space" or try more as one the upload to ftp space.

I would just like to also add a direct response to this "If there is uploading error, you need to fix the reason and then start upload process again"

That's what we're asking.. actually how to start the upload process again? There does not seem to be a way to do this without redoing the whole backup process.

Hi I would like to add that this would be a great feature. My backups regularly fail to upload to FTP on Plesk 12.5.30. When this happens the only way I can fix it is to delete the backup and run it again. My backups are about 20Gb and takes a long time to create. It would be very nice to be able to retry the ftp upload process via the Plesk interface, or know which files I need to move from /var/lib/psa/dumps/ to make this happen.

Saying, download the file and upload "should download backup from server and upload handy [manually]" is not really an option. 20Gb is too much. Even if it weren't, how would Plesk know I had put it in ftp storage?

My ftp storage is actually on the same server, I then move the backup file to Amazon S3 using a cron jon.

Please Plesk, the backup feature needs some love and brought up to date with modern technologies!

As explained for instance at https://talk.plesk.com/threads/personal-ftp-repository-backup-failing-on-upload.335299/#post-804534 sometimes full server backups fail. In this case, the backups are stored locally on the server even though the backup was meant to be stored on the FTP server. Now you have two issues:
a) The backup is stored locally, but not as a single file (compared to the FTP backup files). Thus you cannot simply move the file from local storage to the remote FTP server. In addition, it is unclear whether Backup Manager will recognize that the backup has been moved.
b) The (broken) part of the uploaded file is still there and shown in the Backup Manager.

when i fix the reason of upload error, i should download backup from server and upload handy.

example:
The following error occurred during the scheduled backup process:

Unable to rotate dump: The dump rotation is failed with code '151' at /usr/local/psa/admin/bin/plesk_agent_manager line 1224.
; Unable to upload dump to FTP, it remains in server repository and you can manually download and upload it to FTP. Upload diagnostic message: Repository error: Unable to save data to an archive. Check whether the target directory is accessible for writing. For more information, see the log file (/usr/local/psa/PMM/sessions/2016-06-08-011427.99/migration.log)