python-dev installation error: ImportError: No module named apt_pkg

Question

I am Debian user, and I want to install python-dev, but when I run the code in the shell as a root:

# aptitude install python-dev

I get the following error:

Traceback (most recent call last):       
  File "/usr/bin/apt-listchanges", line 28, in <module>
    import apt_pkg
ImportError: No module named apt_pkg

What seems to be the problem and how can I resolve it?

Solution 1

Make sure you have a working python-apt package. You could try and remove and install that package again to fix the problem with apt_pkg.so not being located.

apt-get install python-apt

Solution 2

I met this problem when doing sudo apt-get update. My env is debian8, with python2.7 + 3.4(default) + 3.5.

The following code will only re-create a apt_pkg....so file for python 3.5

sudo apt-get install python3-apt --reinstall

The following code solved my problem,

cd /usr/lib/python3/dist-packages
sudo ln -s apt_pkg.cpython-{your-version-number}-x86_64-linux-gnu.so apt_pkg.so

Replace {your-version-number} appropriately.

CAUTION, the following will create a symlink from apt_pkg37m to apt_pkg36m. make sure you are linking to the correct, or at least to an existing version by ll apt_pkg.cpython-*, and see which one(s) you have installed.

sudo ln -s apt_pkg.cpython-{36m,37m}-x86_64-linux-gnu.so

So, obviously, python3-apt checks the highest python version, instead of the current python version in use.

Solution 3

Solve it by this:

cd /usr/lib/python3/dist-packages
cp apt_pkg.cpython-34m-i386-linux-gnu.so apt_pkg.so

Or:

cd /usr/lib/python3/dist-packages
cp apt_pkg.cpython-35m-x86_64-linux-gnu.so apt_pkg.so

Basically, if you get a No such file or directory just ls to try to get the right name.

Solution 4

This happened to me on Ubuntu 18.04.2 after I tried to install Python3.7 from the deadsnakes repo.

Solution was this

1) cd /usr/lib/python3/dist-packages/

2) sudo ln -s apt_pkg.cpython-36m-x86_64-linux-gnu.so apt_pkg.so

Solution 5

This error will often occur when a newer version of python has been installed alongside an older version e.g;

• Ubuntu 18.04.1 ships with python version 3.6.6
• Installed ppa:deadsnakes/python3.7.1 or alternative

• Run a command that uses the apt_pkg module and get an error such as;

      from CommandNotFound.db.db import SqliteDatabase
  File "/usr/lib/python3/dist-packages/CommandNotFound/db/db.py", line 5, in <module>
      import apt_pkg
  

When we install a non-distro python3 version with apt it will set a shared module directory to be that of python3 most usually it will be /usr/lib/python3.

Most of the time this will be ok, but under some circumstances the different versions of python rely on different libraries or shared objects/libraries than the other python version does, so as other answers have pointed out we need to link the .SO to the correct python version. So if we have python3.6 installed on a 64bit system then the apt_pkg .SO link would be

sudo ln -s apt_pkg.cpython-36m-x86_64-linux-gnu.so apt_pkg.so

But the problem lies in the fact that when we install a newer python version the link will update to point to the newest python version, which leads to the error of apt_pkg module not being found. By checking which version of python ships with your distro you can create the link as shown above. Or we use a method to offer the command a choice of python versions to link the .SO such as;

sudo ln -s apt_pkg.cpython-{36m,35m,34m}-x86_64-linux-gnu.so apt_pkg.so

Because python will create this link to the newest installed python version we give the command the option to choose from 3 python versions, of which it will choose the highest version given.

View more solutions

Comments

[Belphegor]

It is already installed. When I hit: # apt-get install python-apt it gives me Reading package lists... Done Building dependency tree Reading state information... Done python-apt is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. And when I try again with: # aptitude install python-dev It gives me the same error again. Some other ideas what should I do?

[Arnestig]

remove it using apt-get remove --purge python-apt and install it again

[Al R.]

Be aware of other dependencies. I removed the package (too) quickly in Ubuntu and lots of other dependencies were removed as well (e.g. ubuntu-desktop). It's my fault for not paying attention to the notes in the log, however.

[Arnestig]

Not really sure if it was due to python-apt. Look over at packages.ubuntu.com/lucid/ubuntu-desktop for dependencies to ubuntu-desktop.

[alvas]

@Arnestig REMOVING python-apt sounds rather dangerous!! Learnt my lesson once and I shall not try it.

[Pamungkas Jayuda]

remove python3 is bad idea :( if you want link to python 3.4 use : ln -s /usr/bin/python3.4 /usr/bin/python3

[desaiankitb]

sudo ln -s apt_pkg.cpython-{35m,34m}-x86_64-linux-gnu.so should be changed to sudo ln -s apt_pkg.cpython-{35m,34m}-x86_64-linux-gnu.so apt_pkg.so

[Alex Gurrola]

You are amazing! For me, it was sudo ln -s apt_pkg.cpython-{35m,36m}-x86_64-linux-gnu.so for python3.6, and this horrific bug is now gone.

[Philippe C]

I needed to run sudo ln -s apt_pkg.cpython-{35m,34m}-x86_64-linux-gnu.so apt

[Jamie Lindsey]

It's never a good idea to tell people to remove things from there system unless it is really needed. Luckily /usr/bin/python3 is normally just a symbolic link anyway. I really think you should just delete this answer.

[dpapadopoulos]

Try to be more specific and explain what these two commands are doing.

[abulka]

After installing Python 3.7 next to the default 3.6 in Ubuntu 18.04 with sudo apt install python3.7 I got this apt_pkg error trying to run pip, so I needed to run cd /usr/lib/python3/dist-packages then sudo ln -s apt_pkg.cpython-{36m,37m}-x86_64-linux-gnu.so then sudo apt install python3-pip.

[StatguyUser]

for python 3.6, command will be sudo ln -s apt_pkg.cpython-{35m,36m}-x86_64-linux-gnu.so

[CloseISQ]

Running 18.04.2, your first recommendation worked for me and I could finally run the sudo apt-get update with no errors. Your second recommendation return an error saying apt-get.so was not a folder.

[Naren Yellavula]

On Ubuntu 18.04, use this $ cd /usr/lib/python3/dist-packages $ sudo cp apt_pkg.cpython-36m-x86_64-linux-gnu.so apt_pkg.so

[Pynchia]

how do you downgrade it?

[vineeshvs]

@AlexGurrola Verified in Ubuntu 16.04 on 22Aug2019

[Abhimanyu]

Compiling python worked for me, here is the link github.com/pypa/pip/issues/5367#issue-320060428

[Leonardo Isso]

This worked for me as well... I listed all the files on the /usr/lib/python3/dist-packages, and I saw that I didn't have of apt_pkg.cpython-34m-i386-linux-gnu.so or apt_pkg.cpython-3m-i386-linux-gnu.so, but I had apt_pkg.cpython-36m-i386-linux-gnu.so... I copied this file to apt_pkg.so and worked perfectly! Thanks!

[AnthonyD973]

Just wanted to confirm to others that this indeed worked for me.

[David Medinets]

why is the downgrade the safest actin?

[CpILL]

Fixed that error, now I'm getting ImportError: cannot import name '_gi' from 'gi' (/usr/lib/python3/dist-packages/gi/__init__.py) :(..

[loretoparisi]

that's crazy, thank you! When in docker: RUN ln -s /usr/lib/python3/dist-packages/apt_pkg.cpython-36m-x86_64-li‌​nux-gnu.so /usr/lib/python3/dist-packages/apt_pkg.so

[w3Develops]

This worked for me as well. As @LeonardoIsso did I also listed all files to find the proper file name because i am on 32 bit Linux.

[Hugo Sohm]

This worked for me with python3.6 but when I revert to python3.7, the error is still there

[jumbot]

This fixed my problem. This solves the problem if it was caused by switching the Python version from 3.6 to 3.7.

[Scipio]

Thanks, had the same issue! Consider using sudo ln -s apt_pkg.cpython-36m-x86_64-linux-gnu.so apt_pkg.so so it's clear what apt_pkg.so is.

[Boris Verkhovskiy]

@Arnestig thank you, --purge and then reinstalling seems to have fixed it for me

[Daniel]

Worked, but I had to change it to sudo cp apt_pkg.cpython-37m-x86_64-linux-gnu.so apt_pkg.so for some reason

[JOHN]

this is the solution! After upgrading to python 3.7.

[pauljohn32]

This was correct fix for me. I caused this problem by using pip3 as root, even though I knew it was a bad idea. I wanted to see how badly I'd get shocked if I put my finger in a light socket. Answer is: pretty bad. Also messing with the /etc/alternatives setup is not for the feint of heart. Not for anybody who is a part time visitor. I think crossing what python link pointed at which python was problem that started me down path to disaster.

[RJaus]

18.04.04, upgrading to python 3.7 and this worked for me as well! Thanks!!

[Henry Palacios]

This worked for me after upgrade python 3.8 on ubuntu18.04.

[allyourcode]

What does the ln command do? I have never seen braces used that way before. Looks like some kind of black magic.

[Sergey Shubin]

It looks like this solution was already proposed in at least 6 another answers to this question (and 3 more just suggested to copy the file instead of symlinking).

[Hao Yellow]

this simply works for me, thanks! One thing is before that we need to cd /usr/lib/python3/dist-packages

[Carlos A. Ibarra]

Those braces are not a property of the the ln command. They invoke shell brace expansion, see gnu.org/software/bash/manual/html_node/Brace-Expansion.html

[user2080866]

Works for python 3.8 also !

[Hassan Ajaz]

very helpful for new python users.

[fcm]

Not working after upgrade from 3.5 to 3.9.

[Tanishq Vyas]

Thanks a lot, it worked for me for python3.7

[XavierStuvw]

This worked for me with Python 3.8.5 with Ubuntu 20.04; the cause for trouble was having played around with the targets py2/py3 of the symbolic link /bin/usr/python. This confused some programs calling py3 which threw the OP's error. The other answer stackoverflow.com/a/64241654/5459638 contains useful information to understand what happened.

[Andre Leon Rangel]

at least reinstall is safer... sudo apt install --reinstall python3

[Andre Leon Rangel]

please add mode details to this answer. Did it work for you? what is this trying to achieve?

[Andre Leon Rangel]

please provide an answer here. You could copy and paste the commands and keep the link

[Sylvain]

for me no 'm', just the python version number apt_pkg.cpython-38-x86_64-linux-gnu.so.

[Feline]

The accepted solution didn't work, but this one did.

[Levin]

This works for me

[siddhusingh]

works for me as well

[Dan Nissenbaum]

This one worked for me on Ubuntu 20.02 after upgrading the default Python to Python 3.9

[Carlos Carvalheira]

Same Reason here !! Thanks