As no trick mentioned here worked ... I made a fresh install and updated everything except the kernel (which remains at 4.15.0-20). And my Lenovo T 520 works again.
So indeed kernel 4.15.0-24 seems the culprit. No glue why booting to previous installed kernels doesn't work either as soon 4.15.0-24 is installed. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1779827 Title: failure to boot with linux-image-4.15.0-24-generic To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1779827/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs