Déjà Dup

Backup failed with unknown error

Asked by brumman

I've been doing backups for 6 months without problems but today it failed. Here is the traceback:

    https://pastebin.ubuntu.com/p/r4ZVj6FnZN/

I am going to upgrade from Ub16 LTS but in meantime have been getting security updates using ESM . These are also failing to install - sticking at generating grub configuration file .. Same is happening with Synaptic Package Manager.
Is some process on hold and also preventing the backup?

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Michael Terry (mterry) said : 		#1

Huh. I'm going to guess that your backup issue is separate from your security update issue.

The traceback you posted makes me think that a manifest file that we write (you'll see some files in your storage location named *.manifest*) is corrupted / can't be parsed.

Is there a recent manifest file in your backup location that looks odd? 16.04 is going to have a pretty ancient duplicity & deja-dup though. I don't remember any known bugs around manifests, but it's possible I've just forgotten one.

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Michael Terry (mterry) said : 		#2

If the error already happened when writing the manifest, one path forward is to delete the latest snapshot we wrote (or for safety, moving those files to a different folder). You can see the latest fileset of duplicity-* files, they'll all have the same timestamp in their name. And then maybe also delete ~/.cache/deja-dup/

If the error is happening because we are having trouble parsing a valid manifest because of some bug, you could always try installing the snap release of deja-dup to get the latest and greatest. Might have a bug fix around manifest parsing?

snap install deja-dup --classic
apt-get remove deja-dup

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brumman (brummancanada) said : 		#3

Thanks Michael,
The latest manifest file I see was on Sep9 and it looks OK I think.
The latest should be Sep23 but that backup failed

By timestamp in the file name do you mean this: 20210901 to 20210910
 eg. /media/brumman/backup ub16/duplicity-inc.20210901T030447Z.to.20210910T032751Z.vol1.difftar.gz
all files with that time span were backed up on Sep 9.

So move all those files including the manifest and duplicity-new-signatures out of the backup?
If I remove deja-dup and install the snap version will all the backups since April be lost?

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Michael Terry (mterry) said : 		#4

> By timestamp in the file name do you mean this: 20210901 to 20210910

Right, exactlly.

> So move all those files including the manifest and duplicity-new-signatures out of the backup?

That was my sugggestion yeah - and maybe also move or delete ~/.cache/deja-dup at the same time, since it has some local copies of some of the backup manifest data.

Once moved, duplicity & Deja Dup will act like they never existed. It won't explain _why_ something went wrong - but our first priority is getting your backups working again.

> If I remove deja-dup and install the snap version will all the backups since April be lost?

Naw don't worry, uninstalling deja-dup will not affect your backup files at all.

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brumman (brummancanada) said (last edit ): 		#5

Thanks again Michael - it worked! I moved the latest files and the cache/deja-dup but did not install the snap version. That version may contain files that are for later versions than Ubuntu16.04 and so cause problems and prevent the upgrade - this already happened with some other program latest installs. Anyway the backup worked and so there probably is no bug in the16.04 duplicity & deja-dup.