Kernel Panic : VFS :Unable to mount root fs on unknown-block (Raspian)

OK, this might not be on the Arduino, but it may come in handy anyway.

“Raspian unable to mount root fs
Kernel Panic : VFS :Unable to mount root fs on unknown-block”

I use the Raspberri Pi as a file server and I can tell you that it is a fickle machine.
After some problems I encountered with it, I decided to do a reinstall with Raspian.
So far so good, that worked.
But then I decided to hook up the second hard-drive again, as I had in the past. The result was that the raspberry was nowhere to be found in my network again.
Attaching a monitor showed it just stopped booting halfway, giving the errors:
Raspian unable to mount root fs
Kernel Panic : VFS :Unable to mount root fs on unknown-block

I learned that this probably has to do with the fact that a load on the USB ports may actually cause your file system to corrupt and quite a number of people are experiencing this.
Obviously I was not looking forward to do a re-install again

The solution I found was to remove the SD card from the raspberry and insert it in my ubuntu desktop for a repair with fsck.

My card had the following partitions and was mounted as dev/sdb


As I wasnt sure which partition was the one broken, I cautiously tried them all. Cautiously means that if I got any warnings, I stopped and moved on the the next partition. What I was looking for was for the fsck to recognize faults and offer to repair and not to cause more problems by me ignoring warnings

In the end it turned out to be partitions 7.
The command “sudo e2fsck -f -v /dev/sdb7”
did the trick. I just answered all the questions with ‘yes’ and when i inserted the card in the raspberry again, I got some auto repair messages and delete of unnecessary files messages and it would start up again, seemingly with all the installed packages (such as webmin) available again

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