The Raspberry Pi company are certainly correct that this would be an Ubuntu / Debian issue (RaspiOS né Raspbian doesn't use flash-kernel to install its kernel on the boot partition). However, the "/boot/dtb-" link is worrying (after the dash should come a kernel version) and suggests something rather more serious is amiss.
Can I ask which Ubuntu image you're using specifically, and exactly how it's installed? (the fact that f-k is complaining about "operation not permitted" when it's running as root suggests something like a boot partition being mounted read-only). ** Changed in: flash-kernel (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/1926186 Title: Kernel crashes Raspberry PI 3B+ To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/flash-kernel/+bug/1926186/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs