I ran into this last night, but only on one computer. My file server without a GUI updated just fine. My main desktop, however, wouldn’t boot.
This is how I fixed it. The problem is the /boot/grub2/grub.cfg file isn’t set quite right. The main problem is the root partition’s UUID isn’t set at all. There is a secondary problem where the resume partition is set wrong. The problem line in grub.cfg looks something like this:
linux vmlinuz-4.1.20-11-default root=UUID= resume=/dev/sdb2 splash=silent quiet showopts
What I did was to boot with the installation DVD and go through to the point just after the installer asks for my partition password. Once it does that, all devices are set so we can look at them. Drop into console with Ctrl-Alt-F2. We need to determine the UUID of root. Look in /dev/mapper and /dev/disk/by-uuid to find out what this is. I use an encrypted LVM for root, and I know it’s name, so it’s easy to find. The UUID is a long hex string, such as:
3f07e22b-fb69-4906-85f6-de7b0b0ce6a2
The symlink /dev/myvg/root will point to something like /dev/dm-3. Find out which symlink in /dev/disk/by-uuid also points to /dev/dm-3. You now have the UUID.
Then, if you don’t know your resume partition (usually swap), you’ll need to mount your root somewhere and look at /etc/fstab and possibly /etc/crypttab to get that. I knew mine. Possibly, if you don’t know and can’t find out what that is, change the bit to “noresume”, though I can’t verify that works. Try it anyway.
Put that UUID into place and fix the resume partition. My correct line looks like this:
linux vmlinuz-4.1.20-11-default root=UUID=3f07e22b-fb69-4906-85f6-de7b0b0ce6a2 resume=/dev/mapper/cr_swap splash=silent quiet showopts
There will be a second place this shows up, so fix that one as well.
Once I fixed the UUID, boot happened normally.
I suspect the real bug is in the script /etc/grub.d/10_linux which actually generates the bits of grub.cfg, but I don’t know enough to say how to fix that.