Which hardware are you on? I'm seeing exactly the same behavior on Ubuntu 19.10 and KDE Neon on Lenovo Ideapad S340-14API with AMD Ryzen 3200U / Radeon Vega Mobile Gfx on board.
The 5.3.0-28 kernel works just fine, while 5.3.0-40 shows the following effect: - on Ubuntu 19.10, booting never ends due to random "BUG: soft lockup - CPU#xx stuck for 23s! [system-udevd:383]" events, thus causing various jobs/services to hang forever; - on KDE Neon, I'm seeing failures with amdgpu driver somewhere in amdgpu_mm_rreg with a call trace ending with gfx_v9_0_set_safe_mode() call. Appreciate any input. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1863759 Title: CPUs stuck during boot after 19.10 upgrade to 5.3.0-40 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1863759/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs