Facing this as well. Upgrade from 20.04 to 21.04 went OK (minor issue with `openmpi-bin`). Currently upgrading from 21.04 to 21.10 and have been waiting on "Searching for obsolete software" for almost an hour now (still at 64%).
i5-3570K, 24GB of RAM, one core always at 100% usage. `/var/log/dist- upgrade/apt.log` shows lots of `pkgProblemResolver` going on. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1874272 Title: Stage "searching for obsolete software" takes a very long time (30 minutes) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1874272/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs