Had 2 backups (1 SD card, 1 HDD) for my "Document" folder.
I was trying to replace my GRUB MBR bootloader for REFind's EFI so I could dualboot on a new laptop (and swap-in my old one's SSD without having to reinsall the whole system: Arch). Unfortunately, the boot partition was too small, and needed to be re-sized from 512MB to 1GB. Foolishly, and in a rush, I thought using gparted to change the partition boundaries (shrink the root partition by 512MB from the beginning, and stretch the boot partition to 1GB from the end) was the answer.
I completely forgot that EXT4 has a superblock at the beginning, so now it was gone, and the root partition was completely unmountable -- and fsck was of no use.
So I scramble to find my backups (to decide whether or not I should figure out how to fix this), and realize that tiny little SD card was missing, and my HDD backup was completely unmountable.
Truly, a major fuck-up.
Thankfully, I didn't write anything to the boot partition, so throwing a Hail Mary and simply resizing the partitions back to their exact original sizes (thankfully x2 my TTS history was useful), allowed the root drive to mount without a hitch.
I was close to losing all of my KeepPassXC passwords and private keys due to shear idiocy.
In the end, I set up "cloud" backups (second storage media type, and long and far away), switched to Debian, and continued on my merry way.