I haven't had anything nearly as catastrophic as the above, but as the effective IT department at my house, I've had some scares.
The first was updating the home server (running Ubuntu server). A new dist upgrade had been released, so I hopped onto the server through SSH. After blasting though the recommendation to have a physical terminal up instead of an ssh connection, I started the dist upgrade.
Server reboots normally, so I do a normal apt-get update and upgrade. That in turn regenerates the kernel, so I go for another reboot, but the server doesn't come back up. All attempts to SSH in get denied.
After trekking into the basement and hooking up a monitor and keyboard to the server, I find out that in regenerating, the video drivers (on a server???) were causing a infinite-boot loop. It turns out that the old graphics card I had left in the computer (I just converted an old computer into a server), had somehow screwed up the boot sequence. After adding a "nomodeset" to GRUB, the server was back in operation. From now on I'm always adding it to the GRUB configuration for a server :facepalm:
The second occured when I was backing up photos. I somehow got this great idea that I would sync all the photos in the house and back them up centrally with git-annex.
Testing it on my computer, I came up with a satisfactory solution. Moving to my parent's computer, I loaded my script and set it to work. Coming back later, I see the entire photos directory overwritten with Unix-style symlinks. Massive panic ensues.
Turns out that if git-annex is missing a certain executable in PATH, it silently fails, but continues checking in the directory. On Windows, this overwrites the whole directory with symlinks :facepalm: It worked on my computer because of my already developer-friendly PATH/environment.
In the end I managed to restore all the files from a backup, but I still learned my lesson; what works on your computer doesn't always work on others :lol: