gcc and cpp depends on uninstallable packages in Ubuntu 19.10

Question

After upgrading to Eoan, I have some packages that are held back and can not be upgraded. It all seems to come down to cpp and gcc:

$ sudo apt install gcc

The following packages have unmet dependencies:
 gcc : Depends: cpp (= 4:9.2.1-3.1ubuntu1) but 4:8.3.0-1ubuntu3 is to be installed
       Depends: gcc-9 (>= 9.2.1-1~) but it is not going to be installed


$ sudo apt install gcc-9

The following packages have unmet dependencies:
 gcc-9 : Depends: cpp-9 (= 9.2.1-9ubuntu2) but it is not going to be installed
         Depends: gcc-9-base (= 9.2.1-9ubuntu2) but 9.2.1-17ubuntu1~18.04.1 is to be installed


$ sudo apt install gcc-9-base

gcc-9-base is already the newest version (9.2.1-17ubuntu1~18.04.1).

I don't understand nearly enough to interpret in, but here's the output of apt-cache:

$apt-cache policy cpp

cpp:
  Installed: 4:8.3.0-1ubuntu3
  Candidate: 4:9.2.1-3.1ubuntu1
  Version table:
     4:9.2.1-3.1ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu eoan/main amd64 Packages
 *** 4:8.3.0-1ubuntu3 100
        100 /var/lib/dpkg/status


$apt-cache policy cpp-9

cpp-9:
  Installed: (none)
  Candidate: 9.2.1-9ubuntu2
  Version table:
     9.2.1-9ubuntu2 500
        500 http://archive.ubuntu.com/ubuntu eoan/main amd64 Packages

Can someone help me make sense of what might be going on here? I have disabled all repositories except the default ones, with no success. I've also tried manually installing the version of gcc-9 that seems to come with 19.10 (9.2.1-9ubuntu2), but that only adds insult to injury, as everything else wants 9.2.1-17ubuntu1~18.04.1

Does this answer your question? How do I restore the default repositories? — N0rbert, Jan 08 '20 at 15:34
I've tried disabling all non-standard repositories with no success, so I'm afraid not. Anything else that can help in debugging? — leo, Jan 08 '20 at 19:17

score 0 · Accepted Answer · answered Jan 11 '20 at 17:21

The root problem here was that some packages were installed with a newer version than available in repositories, and becuase a lot of them had critical dependencies, I couldn't just purge and reinstall them.

The solution: To upgrade them all in one monster expression like this sudo apt install lib32gcc1=1:9.2.1-9ubuntu2 lib32stdc++6=9.2.1-9ubuntu2 libasan5=9.2.1-9ubuntu2 libatomic1=9.2.1-9ubuntu2 libcc1-0=9.2.1-9ubuntu2 libgcc1=1:9.2.1-9ubuntu2 libgomp1=9.2.1-9ubuntu2 libitm1=9.2.1-9ubuntu2 liblsan0=9.2.1-9ubuntu2 libstdc++6=9.2.1-9ubuntu2 libtsan0=9.2.1-9ubuntu2 libubsan1=9.2.1-9ubuntu2 libquadmath0=9.2.1-9ubuntu2 .... and so forth.

Before that, I had to use dpkg -r ... to remove packages that were involved in this dependency chain, but not at all available through repos. (This involved traversing down their dependency chains step by step.) I used apt-cache policy to check availability.

gcc and cpp depends on uninstallable packages in Ubuntu 19.10

1 Answers1