APT Software Installation Python – Problem Installing Python-Dev

aptpythonpython-2.7software installation

I am having trouble installing python-dev. It all started when I tried to install another Python package and got the error:

SystemError: Cannot compile 'Python.h'. Perhaps you need to install python-dev.

I tried sudo apt-get install python-dev but got the error:

The following packages have unmet dependencies:
 python-dev : Depends: python2.7-dev (>= 2.7.3) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

So then I tried sudo apt-get install python2.7-dev and got the error:

The following packages have unmet dependencies:
 python2.7-dev : Depends: python2.7 (= 2.7.3-0ubuntu3) but 2.7.3-0ubuntu3.1 is to be installed
                 Depends: libpython2.7 (= 2.7.3-0ubuntu3) but 2.7.3-0ubuntu3.1 is to be installed

I have tried most everything in the post unmet dependencies. I am running Ubuntu 12.04 and I have everything updated. I have done apt-get clean and apt-get autoclean. I have tried apt-get -f install and all variations on that theme. I have cleaned up my PPA. I even tried using Aptitude, and though it did a lot of clean up, the result was the same.

I really want to be able to install python-dev. How can I make this happen? At this point, I am willing to consider extreme options, whatever they may be.

Best Answer

This bit: 

 python2.7-dev : Depends: python2.7 (= 2.7.3-0ubuntu3) but 2.7.3-0ubuntu3.1 is to be installed

suggests that you are using some mismatched repositories, or have some apt-pins in place keeping the version dependencies from lining up. I think, specifically, python-2.7 2.7.3-0ubuntu3.1 is in the Precise-proposed repository and the 2.7.3-0ubuntu3 version is in Precise/main proper, so you may be preferring -proposed for some but not all packages.

Can you edit your question to include the output of:

apt-cache policy python2.7-dev
apt-cache policy python2.7

and maybe:

apt-cache show python2.7

...

Reading the apt-cache output from your pastebin, it looks like you have the python2.7 2.7.3-0ubuntu3.1 from precise-updates/main installed, but python2.7-dev is from precise/main. I think your install media or an earlier "apt-get update" included the precise-updates repository, but it's not in your current sources.list.

I think you'll be able to get the install going after adding precise-updates and then apt-get update. 

echo "deb http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted" | sudo tee -a /etc/apt/sources.list.d/precise-updates.list
sudo apt-get update
sudo apt-get install python2.7-dev
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