Dependency issue

I am receiving some errors whenever I try to apt-get install, it tells me it cannot do so because certain packages are "not going to be installed."

I can neither install those packages, uninstall them, nor uninstall any package.

when I do apt --fix-broken install I receive error "E: Sub-process /usr/bin/dpkg returned an error code (1)"

the packages in question are ROS Noetic packages, so familiarity with ROS installation is helpful.

$ sudo apt-get upgrade

[sudo] password for roth: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt --fix-broken install' to correct these.
The following packages have unmet dependencies:
 python3-rosdep-modules : Depends: python3-rospkg-modules (>= 1.3.0) but it is not installed
                          Depends: python3-catkin-pkg-modules (>= 0.4.0) but it is not installed
                          Depends: python3-rosdistro-modules (>= 0.7.5) but it is not installed
 ros-noetic-rospack : Depends: python3-catkin-pkg-modules but it is not installed
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).

$ sudo apt --fix-broken install:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following additional packages will be installed:
  python3-catkin-pkg-modules python3-rosdistro-modules python3-rospkg-modules
The following NEW packages will be installed:
  python3-catkin-pkg-modules python3-rosdistro-modules python3-rospkg-modules
0 upgraded, 3 newly installed, 0 to remove and 101 not upgraded.
30 not fully installed or removed.
Need to get 0 B/98.0 kB of archives.
After this operation, 650 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
(Reading database ... 247423 files and directories currently installed.)
Preparing to unpack .../python3-catkin-pkg-modules_0.4.24-1_all.deb ...
Unpacking python3-catkin-pkg-modules (0.4.24-1) ...
dpkg: error processing archive /var/cache/apt/archives/python3-catkin-pkg-module
s_0.4.24-1_all.deb (--unpack):
 trying to overwrite '/usr/lib/python3/dist-packages/catkin_pkg/__init__.py', wh
ich is also in package python3-catkin-pkg 0.4.24-1
Preparing to unpack .../python3-rospkg-modules_1.3.0-1_all.deb ...
Unpacking python3-rospkg-modules (1.3.0-1) ...
dpkg: error processing archive /var/cache/apt/archives/python3-rospkg-modules_1.
3.0-1_all.deb (--unpack):
 trying to overwrite '/usr/lib/python3/dist-packages/rospkg/__init__.py', which 
is also in package python3-rospkg 1.2.3-1
Preparing to unpack .../python3-rosdistro-modules_0.8.3-1_all.deb ...
Unpacking python3-rosdistro-modules (0.8.3-1) ...
dpkg: error processing archive /var/cache/apt/archives/python3-rosdistro-modules
_0.8.3-1_all.deb (--unpack):
 trying to overwrite '/usr/lib/python3/dist-packages/rosdistro/__init__.py', whi
ch is also in package python3-rosdistro 0.8.0-1
Errors were encountered while processing:
 /var/cache/apt/archives/python3-catkin-pkg-modules_0.4.24-1_all.deb
 /var/cache/apt/archives/python3-rospkg-modules_1.3.0-1_all.deb
 /var/cache/apt/archives/python3-rosdistro-modules_0.8.3-1_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

Here is the part of the error you need to look at:

dpkg: error processing archive /var/cache/apt/archives/python3-catkin-pkg-module
s_0.4.24-1_all.deb (--unpack):
 trying to overwrite '/usr/lib/python3/dist-packages/catkin_pkg/__init__.py', wh
ich is also in package python3-catkin-pkg 0.4.24-1
Preparing to unpack .../python3-rospkg-modules_1.3.0-1_all.deb ...
Unpacking python3-rospkg-modules (1.3.0-1) ...
dpkg: error processing archive /var/cache/apt/archives/python3-rospkg-modules_1.
3.0-1_all.deb (--unpack):
 trying to overwrite '/usr/lib/python3/dist-packages/rospkg/__init__.py', which 
is also in package python3-rospkg 1.2.3-1
Preparing to unpack .../python3-rosdistro-modules_0.8.3-1_all.deb ...
Unpacking python3-rosdistro-modules (0.8.3-1) ...
dpkg: error processing archive /var/cache/apt/archives/python3-rosdistro-modules
_0.8.3-1_all.deb (--unpack):
 trying to overwrite '/usr/lib/python3/dist-packages/rosdistro/__init__.py', whi
ch is also in package python3-rosdistro 0.8.0-1
Errors were encountered while processing:
 /var/cache/apt/archives/python3-catkin-pkg-modules_0.4.24-1_all.deb
 /var/cache/apt/archives/python3-rospkg-modules_1.3.0-1_all.deb
 /var/cache/apt/archives/python3-rosdistro-modules_0.8.3-1_all.deb

The error message clearly says that it is trying to overwrite a few files because there is a package that has already created those files. In simple words, the package was supposed to place one of its files in /usr/lib/python3/, but it was shocked to see that those files were already there. It didn't know what to do next, so it started throwing error messages.

If you look carefully, you will see that those packages are placed in /var/cache/apt/archives/. This is apt's cache directory, where it downloads files and waits for dpkg to install them (process them). As they are stored in apt's cache, you'll see that every time you use apt, dpkg starts processing those files (packages).

How to solve the problem?

You can use three different types of commands to solve this problem:

1. Use dpkg -P to purge packages and fix everything safely (almost...).

   The -P in dpkg means --purge and will remove everything, including settings and configuration files.

   In your case you need to force overwrite:

   dpkg -i --force-overwrite /var/cache/apt/archives/python3-catkin-pkg-modules_0.4.24-1_all.deb
   dpkg -i --force-overwrite /var/cache/apt/archives/python3-rospkg-modules_1.3.0-1_all.deb
   dpkg -i --force-overwrite /var/cache/apt/archives/python3-rosdistro-modules_0.8.3-1_all.deb
   

   Then run:

   sudo apt -f install
   

2. Use dpkg -i --force-overwrite <file> to make it safer.

   In your case you need to force overwrite:

   dpkg -i --force-overwrite /var/cache/apt/archives/python3-catkin-pkg-modules_0.4.24-1_all.deb
   dpkg -i --force-overwrite /var/cache/apt/archives/python3-rospkg-modules_1.3.0-1_all.deb
   dpkg -i --force-overwrite /var/cache/apt/archives/python3-rosdistro-modules_0.8.3-1_all.deb
   

   Then run:

   sudo apt -f install
   

3. Use rm to remove those package files (kinda dangerous).

   You can remove all those .deb package files by running:

   sudo rm -r /var/cache/apt/archives/*.deb
   

   Then run:

   sudo apt -f install
   

Notes:

• Only use one of these methods.
• 1st and 2nd are recommended.

Be careful!

• Overwriting things can cause serious trouble if the files are different. One of your conflicting packages will no longer function properly.

• Dependencies not installed manually will be removed when no packages that are installed depend on them.

• Generally, if any problem occurs, then running:

  sudo apt install python3-all
  

  will work (at least on Ubuntu 21.10)