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I am new to Duplicity and trying to test it as a new backup tool. However, I have found that it permits incremental backups with new symmetric passphrases which then causes the backup to be unrecoverable. For instance, this is my test script:

#!/bin/bash

PASSPHRASE=one duplicity full /home/ken/scripts file:///home/ken/tmp/
read -p "Press [Enter] key to start incremental backup..."
PASSPHRASE=two duplicity incr /home/ken/scripts file:///home/ken/tmp/

duplicity verify file:///home/ken/tmp/ /home/ken/scripts

Trying to run the verify line causes this result:

Local and Remote metadata are synchronized, no sync needed.
Last full backup date: Fri Apr 15 18:15:41 2022
GnuPG passphrase for decryption: 
GPGError: GPG Failed, see log below:
===== Begin GnuPG log =====
gpg: AES256.CFB encrypted data
gpg: encrypted with 1 passphrase
gpg: decryption failed: Bad session key
===== End GnuPG log =====

I would have expected on the incremental backup for Duplicity to check the passphrase matched the passphrase of the original full backup.

Is this a bug or a feature?

How can I ensure my incremental backups are performed consistently with the previous backup so I don't corrupt my backup files?

kmccoy
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1 Answers1

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This problem affected me, and with real data.

I believe this is fixed in the most recent versions; see the gitlab posts linked to below.

But I note that, as of mid-November 2022, if I just install on Ubuntu 22.04 via apt install, it does not get the most recent version, so you may have to go elsewhere to get the most recent version.

https://gitlab.com/duplicity/duplicity/-/issues/147

Eric
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  • Hello @Eric, welcome to SF! This answer contains mostly useful information, but it could be improved: - Put a short answer to the question(s) first. - Try to extract and write relevant information from linked sites. - Try to keep anecdotes at the end. – P.Péter Nov 24 '22 at 09:01