Comment 3 for bug 1875407

I think this is occurring because /boot is filling up. I have a boot partition sized to defaults by the Unbuntu installer. That's 721392 1K-blocks per df. Lately, as 20.04.3 has picked up newer kernels, too many have been retained. I had associated files for one 5.10.0, one 5.11.0, and two 5.13.0 on there. `apt autoremove` didn't affect those retained. I believe that left initramfs-tools with too little space to update an existing version. Most of the space are the initrd.img files.