This issues is a perennial one, here is one of the classic questions and answers, althought there are some nuances that might need some answers:
Not enough free disk space on /boot
The 'not enough free space' message appeared when upgrading, and I'm a bit concerned, and don't know if there are any issues in rebooting.
It seems my machine (20.04 LTS) has updated, but, since it hasn't rebooted in a few days, doing a 'uname -r' still shows the older kernel in use:
me@home:uname -r
5.15.0-73-generic
Doing an ls -l on /boot shows the new kernel (-75), and of course, the old one. Another machine (also running 20.04 LTS) I've got shows the exact same sizes for System.map-5.15.0-75-generic, and vmlinuz-5.15.0-75-generic (although initrd.img-5.15.0-73 and -75.generic on the other machine is different; the sizes are close, but smaller; 1285887067 and 128598091), and config-5.15.0-73 and -75 are the same. Is it correct to assume that the new kernel has been downloaded and is ready to go?
rwxr-xr-x 5 root root 4096 Jun 22 06:39 .
drwxr-xr-x 20 root root 4096 Sep 29 2014 ..
-rw-r--r-- 1 root root 262214 May 17 10:12 config-5.15.0-73-generic
-rw-r--r-- 1 root root 262224 Jun 7 15:21 config-5.15.0-75-generic
drwx------ 2 root root 4096 Dec 31 1969 efi
drwxr-xr-x 4 root root 4096 Jun 22 06:39 grub
lrwxrwxrwx 1 root root 28 Jun 22 06:36 initrd.img -> initrd.img-5.15.0-75-generic
-rw-r--r-- 1 root root 177971432 Jun 8 00:10 initrd.img-5.15.0-73-generic
-rw-r--r-- 1 root root 177979513 Jun 22 06:37 initrd.img-5.15.0-75-generic
lrwxrwxrwx 1 root root 28 Jun 22 06:36 initrd.img.old -> initrd.img-5.15.0-73-generic
drwx------ 2 root root 16384 Nov 26 2020 lost+found
-rw-r--r-- 1 root root 182704 Aug 18 2020 memtest86+.bin
-rw-r--r-- 1 root root 184380 Aug 18 2020 memtest86+.elf
-rw-r--r-- 1 root root 184884 Aug 18 2020 memtest86+_multiboot.bin
-rw------- 1 root root 6229204 May 17 10:12 System.map-5.15.0-73-generic
-rw------- 1 root root 6230131 Jun 7 15:21 System.map-5.15.0-75-generic
lrwxrwxrwx 1 root root 25 Jun 22 06:36 vmlinuz -> vmlinuz-5.15.0-75-generic
-rw------- 1 root root 11473896 May 17 10:16 vmlinuz-5.15.0-73-generic
-rw------- 1 root root 11493608 Jun 7 15:23 vmlinuz-5.15.0-75-generic
lrwxrwxrwx 1 root root 25 Jun 22 06:36 vmlinuz.old -> vmlinuz-5.15.0-73-generic
The nuances:
Is the system OK to be restarted? Is there a way to know if the kernel has been downloaded correctly? The worst case scenario is we have to reboot with the old kernel, as per: How can I boot with an older kernel version?
Why would we get an error about boot size, if there are only two kernels (-73 and -75), and there does seem to be room in /boot:
me@home: /boot$ df -h /boot
Filesystem Size Used Avail Use% Mounted on
/dev/sda5 703M 382M 270M 59% /boot
For resizing /boot, it seems that you can boot off of an Ubuntu Live USB and run gparted from there. My system boots to a screen that asks for a password 'Please unlock disk sda6_crypt' first. This may be a separate question, but it seems related - can you resize /boot even if encrypted? A note here is from 16.04, not 20.04: resize an encrypted disk? ; surely there must be others who have a similar setup.
