The mirror of the ubuntu archive which you are using is out of date and does not have Ubuntu 20.04 LTS (focal) on it so the upgrade can not proceed. You'll need to switch to an up to date mirror of the Ubuntu archive for the upgrade to be possible, you can find a list at https://launchpad.net/ubuntu/+archivemirrors.
2020-04-25 22:58:45,102 DEBUG examining: 'deb http://ubuntu.uc3m.es/ubuntu/ eoan main' 2020-04-25 22:58:45,103 DEBUG verifySourcesListEntry: deb http://ubuntu.uc3m.es/ubuntu/ focal main 2020-04-25 22:58:45,103 DEBUG url_downloadable: http://ubuntu.uc3m.es/ubuntu//dists/focal/Release 2020-04-25 22:58:45,103 DEBUG s='http' n='ubuntu.uc3m.es' p='/ubuntu//dists/focal/Release' q='' f='' 2020-04-25 22:58:45,920 DEBUG error from httplib: 'HTTP Error 404: Not Found' Additionally, I'll work on getting this mirror of the archive delisted. ** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1875095 Title: crashes To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1875095/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
