So I'm running Ubuntu 18.04 on a btrfs root. I recently rebooted because I got a notification about "restart required" after an update. The last few times I restarted this server, I had an issue where the kernel wouldn't load and I ended up in grub, and loaded the last kernel manually. This time (I had definitely run update-grub since last time) I'm in grub rescue and the usual commands don't work, so I looked at a tutorial, but when I get to insmod normal, I get the error "Compression type 0x3 not supported", and then normal yields command not found. I'm writing this post because apparently nobody has ever seen this error* and I can't figure out what it means or how to fix it. My system works fine with kernel 4.15.0-23 but not at all with 4.15.0-24, which somehow got reinstalled after I removed it.

*A web search for the error message in quotes comes up empty

Your Answer


By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.