when I try to update and type:
sudo apt-get update
I get this error
E: Problem executing scripts APT::Update::Post-Invoke-Success 'test -x /usr/bin/apt-show-versions || exit 0 ; apt-show-versions -i' E: Sub-process returned an error code
That sounds like a bug in
If you don't know if you need it you quite likely don't need it.
If you need the program you could at least remove the file
and file a bug report.
I know this thread is old, but because people find it when searching for help I thought I would add another answer. Memory. If you are out of memory you will get this error. You can fix this quickly by adding swap space if you don't already have any.
I have to say I'm a beginner of Ubuntu but try to follow this guide:
Antonio says that it worked! Let's hope it will work for you too, even though the problem maybe isn't the same!