The upgrade is failing to calculate because you have installed sane packages from a PPA and the version of those packages are greater than the ones in the release to which you are trying to upgrade. You'll need to use the ppa-purge package to remove the packages from that PPA and install the official versions of those packages, after that please attempt the upgrade again.
** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1897695 Title: impossible d'évaluer la mise à niveau To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1897695/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs