It's a single 256gb microSD card in the RPi's SD reader (I boot from SSD), which has two partitions: first is an empty 32mb FAT partition, second is a ~256gb exFAT partition which is mounted to the RPISD folder and contains the image.
Which model Raspberry Pi are you using? What operating system?
Have you tried booting from an SD card with a fresh copy of Raspberry Pi OS on it and a USB flash drive formatted ext4 mounted on /media or /mnt and running image-backup?
I don't recall ever having "mkdir: cannot create directory ‘/tmp/img-backup-mnt/boot’: Bad message" reported in the history of Image File Utilities (more than 8 years).
Statistics: Posted by RonR — Mon Dec 29, 2025 5:27 pm