Hi everybody.
I am running a clean install of the very latest Neon.
When I checked for updates today via Discover, there were 173.4mb of updates.
I selected "Update all" and halfway through the update, it fails with this message

Package failed to install
Error while installing package
installed linux-firmware package post-installation script subprocess returned error exit status 1

I reboot my computer and it hangs with these error messages.

VFS cannot open root device "Label Neon" or unknown block (0,0) error-6
Please append a correct "root=" Boot option.
Here are the available options
Kernel panic not syncing VFS unable to mount.
Root FS on unknown - Block(0,0)
End kernel panic not syncing vfs unable to mount root fs on unknown block 0:0

The previous day, I had made a bare metal backup using Redo.
I restored the backup.
Everything seems to work fine, except when I try to do the updates again.
I have repeated this process 3 times, everytime the same.
Any help would be most appreciated.

Mine updated fine and I'm on unstable. Googling returned nothing for me and no-one else has posted the same problem on reddit/bugs/forum/matrix so what is different about your setup?

Try updating in terminal with
$ pkcon refresh && pkcon update to see if it generates any better information and then try
$ sudo apt update && sudo apt upgrade and see if that sheds any light.

And try installing the problem package on it's own:
$ sudo apt install linux-firmware I suggest apt here because it gives more detail than pkcon

I would also try pkcon repair, maybe even try apt's fix function:
$ sudo apt --fix-broken install

Hi robgriff444.
I updated my signature to include info about what I'm running.
Thanks for the suggestions, I will try them out and report back, but right now I need to get some sleep.
I've been up for over 24 hours now.

It may be refind then, and I know nothing about that. What about other SW differences to standard? PPAs etc.

Either your initramfs wiring for refined has a bug or your ESP is full. Looking at the post-inst script it merely calls update-initramfs, that should only fail if it cannot write the new initrd so I'd put my money on full ESP.

After trying all the great suggestions you guys offered and several others I found on the internet, I was almost ready to give up and do a complete reinstall again.
However, in a last-ditch effort, I uninstalled all the plymouth packages and reinstalled them one by one.
if there were install errors with a particular package, I would uninstall the package and go to the next.
When done, everything seems normal with my system now.
There are a few plymouth packages that will not install.
I have no idea why this worked or why they were messed up in the first place.
Thanks guys for the help.