I have just upgraded from 15.04 to 15.10. I was asked if I wanted to have the obsolete packages removed, but since the option was going to take several hours...I decided to choose "no". I have found that it can be done via synaptic too, but is it necessary or useful at all?
3 Answers
Removing obsolete (not used) packages will free a good amount of disk space. it's not necessary, but it's healthy to do these removals to free up disk space.
1I would definitely recommend to first check all the packages that are listed.
I removed "obsolete packages" whilst the update from 16.04 to 18.xx (LTS) Even though I use things like my php server, xchat, virtualBox, I unfortunately let it remove everything and .... it was gone. Fortunately their config files were left there, so a reinstall fixed it in my case. But be careful.
Yes, the package is replaced with a newer version or newer dependencies. So it's recommended to remove obselete after dist-upgrade
