I just reinstalled Ubuntu MATE 15.10 from scratch. I had followed this answer to save a list of installed packages and restore it on the newly installed system.

However, when I do

sudo dpkg --set-selections < packages-backup.list

I get a long list of error messages like these:

dpkg: warning: package not in database at line 1417: sqlite3
dpkg: warning: package not in database at line 1417: sqliteman
dpkg: warning: package not in database at line 1417: sqliteman-doc

and finally

dpkg: warning: found unknown packages; this might mean the available database is outdated, and needs to be updated through a frontend method

So I ran sudo apt-get update and re-ran dpkg but I keep getting the same error.

I seem to get this error message for every single package in the list, including rather unspectacular ones such as the default kernel or sqlite. Also, I had not added any additional PPAs on my previous setup, thus packages from non-default repositories can't be the issue here.

As a test, I tried to install one of the "offending" packages with sudo apt-get install, which worked without any issues.

What's going wrong here?

  • 1
    Did you run sudo apt-get dselect-upgrade? – philsf Jan 29 '16 at 9:51
  • Not yet (as In understand the answer, this would be run afterwards). Just found something similar in the dpkg manpage and ran sudo dselect update, then retried. That reduced the warnings to packages that explicitly state a particular version. – user149408 Jan 29 '16 at 9:57
  • Just executed sudo apt-get dselect-upgrade and it seems to be installing everything that's missing. Looks like all is fine now... – user149408 Jan 29 '16 at 10:00
  • In this case I'll add an answer, then you can close the question. – philsf Jan 29 '16 at 10:03
  • one note on Ubuntu 16.10 desktop install, I had to 'apt-get install dselect' for this to work. – RoundSparrow hilltx Nov 30 '16 at 15:40

The warnings are safe to ignore, as they only concern the dpkg database. Actual installation is done with APT, which doesn't use this database.

When you are using dpkg in this manner, you need to use dselect-upgrade in order to apply the changes marked.

sudo apt-get dselect-upgrade

From man dpkg:

Note that this file is mostly useless if you don't use dselect but an APT-based frontend: APT has its own system to keep track of available packages.

| improve this answer | |
  • Thanks for the answer. Since I run dselect-upgrade after set-selections, I understand I would still get the warnings – are you saying they're safe to ignore as they refer to a package DB that isn't going to be used anyway? – user149408 Jan 29 '16 at 10:28
  • @user149408, that is correct, you can safely ignore those. Trust whatever APT says, which will be the one that manages existing packages from then on. – philsf Jan 29 '16 at 10:32

Try this:

sudo apt-get install dselect && sudo dselect update

After you can execute:

sudo dpkg --set-selections < packages-backup.list
| improve this answer | |

The following script was a workaround for me. Watch out for linux-images and linux-headers. If you have many of those in your dpkglist.txt then you might want to filter these out with grep -v commands like

 cat dpkglist.txt | grep "$l_mode" | grep -v linux-headers | grep -v linux-image-3 | grep -v linux-image-extra-3 | cut -f1

script to install and uninstall packages from dpkglist.txt via apt-get


# get the packages
# param 1: l_mode: install or deinstall
packages() {
  local l_mode="$1"
  # get the lines for the given mode
  cat dpkglist.txt | grep "$l_mode" |  cut -f1

# loop over the packages in the given mode
# param 1: l_mode: install or deinstall
loop() {
  local l_mode="$1"
  for package in $(packages $l_mode)
    case "$l_mode" in
      install) apt-get -y install $package;;
      deinstall) apt-get -y remove $package;;

# do two loops
loop deinstall
loop install
| improve this answer | |

To update dpkg database from apt cache:

apt-get update # can skip this
apt-cache dumpavail > /var/cache/apt/available
dpkg --admindir=/var/lib/dpkg --update-avail /var/cache/apt/available

or one-liner with root

dpkg --admindir=/var/lib/dpkg --update-avail <(apt-cache dumpavail)

This method do not require dselect package

| improve this answer | |

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