Hi
I upgraded LinuxMint from 21.3 to 22 and the upgrade went smoothly.
After more than a week of smooth running, I received a notification of a kernel update to 6.8.40 from 6.8.38.
I decided to go ahead with this upgrade using "sudo apt upgrade"
This command appeared to work initially. But it failed when it came to generating the initrd.img.
The reason for the failure was that there was no '/etc/kernelstub/entries.d' directory.
When I checked the backup of my system, I noticed that there had not been a 'entries.d' subsirectory in '/etc/kernelstub' either in Mint 21.3 before the upgrade or in Mint 22 after the upgrade. There was only a filed called 'system' in the '/etc/kernelstub' directory.
I proceeded to run "sudo kernelstub create" which created the entries.d subdirectory in the '/etc/kernelstub' directory & a file with long name which was basically pointing to the kernel image vmlinuz and the mount point of the root partition,
After doing this, all upgrades started working again like before & my system is running well again.
I'm just putting this here in case anyone else faces the same issue and also to raise the possibility that the upgrade process might be missing a step to create the 'entries.d' subdirectory & the step to run "kernelstub create" to move over to the new (Mint22) way of mounting the root partition.
I could not find any other reports of this issue which leads to me believe that perhaps there is something different about my system. But I can't see what it could be.