process_queue: Assertion `dependtry <= 4' failed.

[Dan Roberts]

In Dapper Drake, whenever I try to install anything through apt-get or synaptic. The last package ALWAYS fails with the following error.

I believe this came about after a recent update through the update manager. However, I don't remember exactly when it started.

dpkg: ../../src/packages.c:191: process_queue: Assertion `dependtry <= 4' failed.
Aborted

[Lionel Dricot (ploum-deactivatedaccount)]

What is your sources.list ? What happen when you do an "apt-get -f install" ?

[Simon Law (sfllaw)]

Hi Dan,

Could you please run dpkg under GDB and produce a backtrace,
as described by https://wiki.ubuntu.com/Backtrace ? The arguments
to run dpkg under GDB should be "run --configure -a"

Then, please attach the output to this bug report using:
https://launchpad.net/distros/ubuntu/+bug/46530/+addattachment

Thanks.

[Dan Roberts (ademan555)]

Simon Law wrote:
> Hi Dan,
>
> Could you please run dpkg under GDB and produce a backtrace,
> as described by https://wiki.ubuntu.com/Backtrace ? The arguments
> to run dpkg under GDB should be "run --configure -a"
>
> Then, please attach the output to this bug report using:
> https://launchpad.net/distros/ubuntu/+bug/46530/+addattachment
>
> Thanks.
>
> ** Changed in: Ubuntu
> Sourcepackagename: None => dpkg
> Status: Unconfirmed => Needs Info
>
> ** Summary changed:
>
> - apt-get fails
> + process_queue: Assertion `dependtry <= 4' failed.
>
I'd be more than happy to do that, out of curiosity (and for future
reference), is that "standard operating procedure" for reporting a bug?
Or is it extra info to help diagnose a problem?

thanks
-Dan

[Dan Roberts (ademan555)]

This may not be totally pertinent. But when I tried to install gdb, it turned out I already had it... but then the error cropped up again, as though the error is unrelated to installation, and is just a part of dpkg

Reading package lists... Done
Building dependency tree... Done
gdb is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
Need to get 0B of archives.
After unpacking 0B of additional disk space will be used.
dpkg: ../../src/packages.c:191: process_queue: Assertion `dependtry <= 4' failed.
E: Sub-process /usr/bin/dpkg exited unexpectedly

If that helps diagnose the problem at all, as for the backtrace, I'll have that in a moment.

cheers
-Dan

[Simon Law (sfllaw)]

Hi Dan,

I asked for the backtrace because it is applicable in this case for
helping the dpkg developers track down their bug. It's not the
right thing to do for all cases, but it is generally useful for crashes
and assertion failures.

Thanks.

[Ian Jackson (ijackson)]

Simon Law writes ("[Bug 46530] Re: apt-get fails"):
> Could you please run dpkg under GDB and produce a backtrace,
> as described by https://wiki.ubuntu.com/Backtrace ? The arguments
> to run dpkg under GDB should be "run --configure -a"

We know what this is and don't need a backtrace. What we'd like to
know is what you were trying to do, copy of your /var/lib/dpkg/status,
etc.

Thanks,
Ian.

[Dan Roberts (ademan555)]

Ian Jackson wrote:
> Simon Law writes ("[Bug 46530] Re: apt-get fails"):
>
>> Could you please run dpkg under GDB and produce a backtrace,
>> as described by https://wiki.ubuntu.com/Backtrace ? The arguments
>> to run dpkg under GDB should be "run --configure -a"
>>
>
> We know what this is and don't need a backtrace. What we'd like to
> know is what you were trying to do, copy of your /var/lib/dpkg/status,
> etc.
>
> Thanks,
> Ian.
>
>
Geeze, I'm really sorry. This kinda reflects badly on me, but I got fed
up and did a reinstall (I lost nothing at that point). My Sincerest
apologies, in the future i'll be sure to stick with a problem if I
report it. If its of any use to you in my reinstall I followed the
exact same pattern EXCEPT I have not updated since I installed my nvidia
driver. I haven't had that problem yet, and I was suspicious it might
have had something to do with that (maybe I even installed incorrectly
and I borked something having to do with dpkg)

Sinceres Apologies,
-Dan

[Ian Jackson (ijackson)]

Dan Roberts writes ("[Bug 46530] Re: [Bug 46530] Re: [Bug 46530] Re: apt-get fails"):
> Geeze, I'm really sorry. This kinda reflects badly on me, but I got fed
> up and did a reinstall (I lost nothing at that point). [...]

No, don't apologise. Thanks for reporting the bug anyway. It is a
useful data point even if we can't investigate it in detail.

Regards,
Ian.

[florg (ubuntu-florg)]

Hi,

just got the same failure. To reproduce on up-to-date dapper:

(1) sudo apt-get remove blt

and then

(2) sudo apt-get install blt

When installed together with the dependencies removed in (1), the package installs correctly.

Regards,
Florian

[florg (ubuntu-florg)]

Just found another package that exhibits this bug, although this one is not as easily reproduced: `python-subversion'

I can reproduce this bug on a fresh server-install while adding packages manually by a script. (I copied the selections from another machine and install them one by one alphabetically; that's how I stumbled upon `blt', too.)

On another computer it's not sufficient to remove python-subversion and reinstall it to reproduce :-/

Maybe it's still good enough to track this bug?

Regards,

Florian

[Dan Roberts (ademan555)]

florg wrote:
> Just found another package that exhibits this bug, although this one is
> not as easily reproduced: `python-subversion'
>
> I can reproduce this bug on a fresh server-install while adding packages
> manually by a script. (I copied the selections from another machine and
> install them one by one alphabetically; that's how I stumbled upon
> `blt', too.)
>
> On another computer it's not sufficient to remove python-subversion and
> reinstall it to reproduce :-/
>
> Maybe it's still good enough to track this bug?
>
> Regards,
>
> Florian
>
>
I know I've reached the end of my usefulness by reporting this bug. But
yeah, I did in fact have the python-subversion package, but it was a
fresh dapper install, but not a server install, just your standard
(dunno what to call that). Does that mean the package is broken? or the
package is breaking dpkg? (Oh, and I used synaptic, so i suppose its
possible my bug came from elsewhere)

cheers
-Dan

[Ian Jackson (ijackson)]

I think that you'll find that when you've got this bug,
  dpkg --configure --pending
will fail in the same way. If so then please attach your
/var/lib/dpkg/status to this bug and then I should be able to
reproduce it.

If not then I'm probably going to need a detailed recipe to reproduce,
including:
 - /var/lib/dpkg/status beforehand
    (you may find this in /var/backups, depending on what
     you did when)
 - exactly what operations you did with a session transcript

Thanks,
Ian.

[florg (ubuntu-florg)]

Just speaking for the package `blt', I'll see about the other one later:

florg@tink:~/tmp$ sudo apt-get remove blt
[...]
florg@tink:~/tmp$ sudo apt-get install blt
[...]
Unpacking blt (from .../blt_2.4z-3ubuntu1_i386.deb) ...
dpkg: ../../src/packages.c:191: process_queue: Assertion `dependtry <= 4' failed.
E: Sub-process /usr/bin/dpkg exited unexpectedly
florg@tink:~/tmp$ sudo dpkg --configure --pending
dpkg: ../../src/packages.c:191: process_queue: Assertion `dependtry <= 4' failed.
Aborted

Attaching status-after-removing-blt and status-after-adding-blt

Regards,

Florian

[florg (ubuntu-florg)]

florg@tink:~/projects/bewerbung/europecv$ sudo apt-get remove blt
Password:
Reading package lists... Done
Building dependency tree... Done
The following packages will be REMOVED
  blt python-epydoc python-tk python-unit python2.4-epydoc python2.4-tk
  python2.4-unit ubuntu-desktop
0 upgraded, 0 newly installed, 8 to remove and 0 not upgraded.
Need to get 0B of archives.
After unpacking 6836kB disk space will be freed.
Do you want to continue [Y/n]?
(Reading database ... 113024 files and directories currently installed.)
Removing ubuntu-desktop ...
Removing python-unit ...
Removing python2.4-unit ...
Removing python-epydoc ...
Removing python2.4-epydoc ...
Removing python-tk ...
Removing python2.4-tk ...
Removing blt ...
florg@tink:~/tmp$ cp /var/lib/dpkg/status status-after-after-removing-blt

[florg (ubuntu-florg)]

florg@tink:~/tmp$ sudo apt-get install blt
Reading package lists... Done
Building dependency tree... Done
Suggested packages:
  blt-demo
The following NEW packages will be installed
  blt
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0B/2050kB of archives.
After unpacking 5046kB of additional disk space will be used.
Selecting previously deselected package blt.
(Reading database ... 112842 files and directories currently installed.)
Unpacking blt (from .../blt_2.4z-3ubuntu1_i386.deb) ...
dpkg: ../../src/packages.c:191: process_queue: Assertion `dependtry <= 4' failed.
E: Sub-process /usr/bin/dpkg exited unexpectedly
florg@tink:~/tmp$ cp /var/lib/dpkg/status status-after-adding-blt

As before the package installs fine if it is installed together with the packages that were removed in `status-after-removing-blt'

florg@tink:~/tmp$ sudo apt-get install blt python-epydoc python-tk python-unit python2.4-epydoc python2.4-tk
Reading package lists... Done
Building dependency tree... Done
The following extra packages will be installed:
  python2.4-unit
Suggested packages:
  blt-demo epydoc-doc tix
The following NEW packages will be installed
  blt python-epydoc python-tk python-unit python2.4-epydoc python2.4-tk
  python2.4-unit
0 upgraded, 7 newly installed, 0 to remove and 0 not upgraded.
[snip]
florg@tink:~/tmp$ sudo dpkg --configure --pending florg@tink:~/tmp$

[Ian Jackson (ijackson)]

florg writes ("[Bug 46530] Re: process_queue: Assertion `dependtry <= 4' failed."):
> Just speaking for the package `blt', I'll see about the other one later:

No need, I think this should be sufficient, thanks. It's almost
certainly just the same bug.

Ian.

[Ian Jackson (ijackson)]

florg writes ("[Bug 46530] Re: process_queue: Assertion `dependtry <= 4' failed."):
> Attaching status-after-removing-blt and status-after-adding-blt

Thank you very much for your help. This has enabled me to fix a bug
which has existed in dpkg since the beginning of time (and which other
people have attempted to fix, but incorrectly, at least twice).

I don't think we'll be putting the fixed verison into Dapper because
we don't want to risk breaking it but if you want the details you can
find them in Debian #370017.

But as a workaround, the blt package could be fixed so that its
dependencies aren't so pathological:

 Package: blt
 Provides: blt-common
 Conflicts: ... blt-common
 Depends: ... blt-common ....

If there are other packages which cause the same problem the same fix
will probably apply, although there are unfortunately some situations
where non-silly dependencies could trigger the dpkg bug.

Ian.

[Colin Watson (cjwatson)]

dpkg 1.13.21ubuntu1 will be available from Edgy once the buildds are fully-operational, and contains:

dpkg (1.13.21) unstable; urgency=low

  [ Guillem Jover ]
  * Disambiguate error message about conflicting command line actions by
    providing both long and short option names. Based on a suggestion by
    Josip Rodin. Closes: #45575
  * Add '/lib32' and '/usr/lib32' to the dpkg-shlibdeps library path search
    list. Closes: #367892
  * Revert usage of English perl non-essential module from install-info.
    Closes: #369928, #369958, #370157, #370174, #370210
  * Print the correct file being parsed by dpkg-parsechangelog's debian
    parser. Closes: #368961
  * Fix dependency cycle breaking in the case when every link involves
    a Provides (Ian Jackson). This is a proper fix for #349442.
    Closes: #370017

  [ Updated dpkg Translations ]
  * Czech (Miroslav Kure).
  * Vietnamese (Clytie Siddall).

 -- Guillem Jover <email address hidden> Sun, 4 Jun 2006 19:02:44 +0300

[pianoboy3333 (pianoboy3333)]

I am confirming this, I have had this error on my machine for about 3 days now, it's driving me insane.

[pianoboy3333 (pianoboy3333)]

Has a way to fix this been released?

[florg (ubuntu-florg)]

Just uninstalling the offending package should put the system into a usable state again.
Another option mentioned e.g. in http://lists.debian.org/debian-devel/1999/08/msg00852.html is to use the `--force-depends' flag while installing/fixing your dependencies as in:

dpkg --configure --force-depends -a

Note that this may introduce more dependency problems :]

[pianoboy3333 (pianoboy3333)]

This sounds good, but I can't figure out what my offending package is! But it does say that I have one package not fully installed or removed, is there a way to find that package with some dpkg command?

[pianoboy3333 (pianoboy3333)]

Update:

I ran `sudo dpkg -l | grep iU' which returned the package python-subversion which was not fully installed. Once I removed that my problems were cured.

[Ian Jackson (ijackson)]

pianoboy3333 writes ("[Bug 46530] Re: process_queue: Assertion `dependtry <= 4' failed."):
> This sounds good, but I can't figure out what my offending package is!
> But it does say that I have one package not fully installed or removed,
> is there a way to find that package with some dpkg command?

dpkg --audit

Ian.

[Adam Conrad (adconrad)]

Opening a dapper task for this, as I'm uploading to dapper-proposed to get this fixed on the buildds (as well as for LTS users)

[Adam Conrad (adconrad)]

Not a bug in blt, however.

[Adam Conrad (adconrad)]

For the record, while this is clearly affecting dapper users, what makes it a bit more critical is that it's also breaking the buildds. Whee.

[Colin Watson (cjwatson)]

It was in fact also a bug in blt's dependencies, but those seem to be less pathological in version 2.4z-4; in particular blt no longer Depends: blt-common.

[Colin Watson (cjwatson)]

For form's sake, here's a stable release update proposal which I've distilled from this bug:

  Impact: Once certain packages have been installed, dpkg will always fail with "process_queue: Assertion `dependtry <= 4' failed." The affected package can be determined using the 'dpkg --audit' command, but this is not typically obvious to end users, so the net result is at best obscure errors on any upgrade.

  Development branch fix: Debian bug 370017, dpkg 1.3.21, merged in Edgy as dpkg 1.3.21ubuntu1; see https://launchpad.net/distros/ubuntu/+source/blt/+bug/46530/comments/18.

  Patch: http://librarian.launchpad.net/4900695/dpkg.diff per Adam above.

mdz approved this on IRC, and I do also.

[Colin Watson (cjwatson)]

Accepted into dapper-proposed. Please test once it lands.

[Adam Conrad (adconrad)]

1.13.11ubuntu7~proposed has been rolled out to the buildds and has, in fact, fixed the problem that prompted me to look into this in the first place.

[Simon Law (sfllaw)]

Verified that dpkg can continue working, and that installing a faulty package like blt will work.

[Adam Conrad (adconrad)]

Uploaded to dapper-updates, waiting on another member of the archive team to approve the upload, to avoid conflict of interest.

 dpkg (1.13.11ubuntu7) dapper-updates; urgency=low
 .
   * Backport Ian Jackson's fix for the assertion failure that occurs when
     dependency cycle breaking fails because every link involves a Provides.
   * This is probably better known to users as the obscure "process_queue:
     Assertion `dependtry <= 4' failed" bug (launchpad.net/bugs/46530)
   * Tested by Simon Law, as well as being extensively tested by me on the
     Ubuntu build daemons for nearly a month; no regressions were noticed.

[Colin Watson (cjwatson)]

Accepted into dapper-updates. Adam, please monitor Launchpad for dpkg bugs for a while per StableReleaseUpdates, and shout if there are any regressions.

[Raphael Michel (rami)]

Bug is also in Intrepid, what can i do (https://bugs.launchpad.net/ubuntu/+source/dpkg/+bug/46530)?

[Mike McNally (m101)]

Also seeing this in Intrepid after a (considerable) batch of updates this morning. The offending package seems to be libc6.

[Mike McNally (m101)]

actually I'm not sure about the offending package; it may have been libxine-x but I have little experience (well OK no experience) in figuring out such things. I uninstalled xine and re-installed, and now my system is OK I think.

[Helge Stenström (h-stenstrom)]

This happened to me too, today, when I ran apt-get update && apt-get dist-upgrade for the first time in about a month. I have a bunch of xine packages installed, and they are listed when I do
dpkg -l | grep -v ^ii | grep -v ^rc

One advice given in http://ubuntuforums.org/showthread.php?t=231752 was to remove offending packages (as per above) with
dpkg --purge remove <those packages listed before>
but I usually use "apt-get remove" or Synaptic to remove packages. Is there a difference?

My hardware is a HP xw9400 with AMD Opteron processor, if that matters.
$ uname -rvm
2.6.27-11-generic #1 SMP Thu Jan 29 19:24:39 UTC 2009 i686
Running Ubuntu 8.10.