Ubuntu crashes with backup of LUKS encrypted disk

Are there special techniques or settings to back up a LUKS encrypted drive with Duplicati?

Ubuntu 20.04 with LUKS encrypted SSD at OS installation

After successfully using Duplicati with unencrypted drive for some years, I have installed a new SSD and reinstalled Ubuntu 20.04 with LUKS full disk encryption.
Now when I use Duplicati to backup to either a local NAS or to Backblaze B2, Ubuntu crashes during the backup. A single file backup runs ok, and restoration of that file works, but a larger backup results in OS crash. Some files and folders have been backed up, but not all. On one occasion screen briefly showed error message “Connection to server lost, attempting again in new…”, when connected to the NAS.

Any tips or suggestions?

Many thanks!

So you have a remote web browser connected to Duplicati on Ubuntu to back Ubuntu up to the NAS? Certainly if you’re directly on the Ubuntu GUI, I’d kind of expect a Ubuntu crash to not give that status.

I suppose you could web search to try to figure out how to diagnose possibly LUKS related crashes. Searching specifically in Duplicati forum and issues didn’t let me spot any such prior Duplicati issue.

Duplicati is just an application program that reads files and file metadata, using a backup destination, database in ~/.config/Duplicati, and various /tmp files. Make sure nothing’s running out of free space. Probably good to watch all system resources. You’ve already tried different destinations, but possibly other files can be moved to non-LUKS storage (if you have any) to see if anything makes crash stop.

Many thanks for your reply and suggestions.

To clarify-

-The setup is a laptop with Ubuntu 20.04 with Duplicati installed backing up the /home directory to a NAS and to Backblaze B2 (Not a remote browser)

-The setup has been successfully working for some years

-A new (replacement) SSD was installed and the setup replicated as near as I could to the previous setup, with the exception of encrypting the full SSD with LUKS when installing Ubuntu

-Data was successfully restored from previous (Duplicati) backups to the new SSD

-New backups were created, again directed to the local NAS and Backblaze B2

-When either of these two backups was run, Ubuntu crashed

-A test backup of a single file ran ok and the file could be restored

Efforts to find a solution -

-this forum(!)

-general web search and search of Ubuntu forums

-test backup of single file (as above)

-backup of /home directory to local NAS using a different backup program

(Deja Dup/Backup) with encryption of the backup file, which ran with no problems

Concerning specific comments-

-There seems to be plenty of drive space- only 180Gb used of 1Tb SSD

-resources- CPUs 25-50% with occasional peak to 90%, Memory 20%

-I don’t have non-LUKS storage. Single SSD, all encrypted

Any other suggestions or comments would be most welcome

The problem is narrowed down to backing up two different folders: /home/snap/thunderbird/ and a folder containing a VMWare virtual machine. These folders were not a problem when backed up with an un-encrypted drive.
When they are excluded, the backup works without any problems.
So now I have a work around. The VMWare machine should perhaps be backed up internally, and the thunderbird email I can back up with an alternative program. I will explore the thunderbird folder more fully to try to find if there is a particular file that causes Ubuntu to crash.

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