Dear Maintainer,

Deb12 has dump 0.4b47-4, and Deb13 has currently 0.4b49-2.

I'm running an automated backup script for years:

https://github.com/PoC-dev/backup

Scenario:
Dump written on Deb12 with dump -0a -b 256 -f - /dev/...

(I'm using 256k blocks for performance reasons, and because I write those dump
files to tape with dd.)

Then access such a file locally with restore -i -b 256 -f ...

restore > ver
verbose mode on
restore > ex
Extract requested files
You have not read any volumes yet.
Unless you know which volume your file(s) are on you should start
with the last volume and work towards the first.
Specify next volume # (none if no more volumes): 1
short compressed block: 262148 expected: 122091355
decompression error, block 262145: data error
Tape decompression error while skipping over inode 5125
continue? [yn] y
Incorrect block for <name unknown> at 3255 blocks
Incorrect block for <name unknown> at 3256 blocks
Incorrect block for <name unknown> at 3257 blocks
...
Incorrect block for <name unknown> at 3414 blocks
short compressed block: 262148 expected: 1835599
decompression error, block 262401: length mismatch
Incorrect block for <name unknown> at 3415 blocks
Incorrect block for <name unknown> at 3416 blocks
Incorrect block for <name unknown> at 3417 blocks
...
Incorrect block for <name unknown> at 6394 blocks
Incorrect block for <name unknown> at 6395 blocks
Segmentation fault

The only way to restore files from dumps is to install the old dump package.

On Tue, 02 Jun 2026 11:34:29 +0200, Patrik Schindler writes:

thank you for the bug report; i'll try to find some time this weekend
to dig deeper into this.

regards
az

tags 1138683 + moreinfo unreproducible
severity 1138683 normal
thanks

On Tue, 02 Jun 2026 11:34:29 +0200, Patrik Schindler writes:
...

i haven't been able to fully or exactly duplicate your problem :-(
(i've tried all kinds of invocations and variants with 2gb
of plain bookworm chroot as backup source...)

without -b 256 none of the backups i've done with the b47 dump
showed any problems when restoring with the b49 version.
(if we can't find a better solution, could you have a check if
omitting the blocksize does provide a workaround for your setup?)

with -b 256, the b49 version threw an 'unsupported compression type 7'
error...but that's as close as i could get to the showstopper you
reported.

slightly better news is that i also tested restoring with the version
in testing and unstable, 0.4b54-1, and that restored older backups with
or without -b just fine.

0.4b54-1 has just been accepted into stable-backports: could you please
have a go at installing that (once it hits the mirrors) and test restores
with that version?

regards
az

Oops, sorry, I've missed your reply. Will test and give you feedback!

:wq! PoC

Hello Alex,

sorry for taking so long.

I could verify that 0.4b54-1 doesn't show the issue, which is an acceptable fix for me.

Are you interested in nailing this down for 0.4b49-2 further or shall we leave it at this?

:wq! PoC

We believe that the bug you reported is fixed in the latest version of
dump, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1138683@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Alexander Zangerl <az@debian.org> (supplier of updated dump package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Tue, 22 Sep 2026 15:38:55 +1000
Source: dump
Architecture: source
Version: 0.4b56-1
Distribution: unstable
Urgency: medium
Maintainer: Alexander Zangerl <az@debian.org>
Changed-By: Alexander Zangerl <az@debian.org>
Closes: 1138683
Changes:
 dump (0.4b56-1) unstable; urgency=medium
 .
   * new upstream release (closes: #1138683)
Checksums-Sha1:
 adf2e0f182dff67706b67dbbc8893729c9c718cb 1922 dump_0.4b56-1.dsc
 c49131eb3f63336622cfe3c4f9bb0b4669b353fd 698845 dump_0.4b56.orig.tar.gz
 dbca5971357dd380dcd106425dce67ab34ee8ac4 12928 dump_0.4b56-1.debian.tar.xz
 f865069a9e9027407eb4d433d4fb92979273a95c 8376 dump_0.4b56-1_amd64.buildinfo
Checksums-Sha256:
 03afa5b1907450b33d2cd50ae2e7e60d97aacf420e31e3f95bb55610e20b59af 1922 dump_0.4b56-1.dsc
 049a7a5b3650ac685c763c5237ae4ad4b640d4e1e2dff95dc487a7988e8d96ac 698845 dump_0.4b56.orig.tar.gz
 8a048648caaee6ed6e4b422208a62639dd8ad999516beab917e13fe762ad274e 12928 dump_0.4b56-1.debian.tar.xz
 f5d93fe72bafe224d99b56e62f3bc841e3916f546fbdb022576be1498f7036db 8376 dump_0.4b56-1_amd64.buildinfo
Files:
 dbfb76f78f23ef7a48e8e4e75a729697 1922 utils optional dump_0.4b56-1.dsc
 a89e9e0b429eabd32dd8afc25cc5f54e 698845 utils optional dump_0.4b56.orig.tar.gz
 b5c75b6a4de2214abdc41b0fff063aee 12928 utils optional dump_0.4b56-1.debian.tar.xz
 9b9c62442ae47d712fc649d1bd4dc7f4 8376 utils optional dump_0.4b56-1_amd64.buildinfo
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On Mon, 21 Sep 2026 17:53:53 +0200, Patrik Schindler writes:

very good, thanks for the feedback.

let's leave it here; i'm about to upload 0.4b56 and will close the bug
with that release.

regards
az