​It’s highly possible that something went wrong while saving them (i.e. when you copied them onto the USB device). Likely scenario is that you unplugged the device before it actually wrote all the data - i.e. didn’t “remove safely” and there was still some data left in the operating system’s cache, or even a cache in the hardware itself.

 

Alternative to that, if the files worked fine from that disc before: It may be that the disc became damaged. Magnetic fields, temperature differences, dampness, hard knocks, etc. all could damage the internals of such drives. Less likely, though still possible: Some bug in the file system (or even just a hardware interference like a spike in power) caused some data to be written into the wrong position at a later stage. I.e. overwriting a portion of said JPG files.

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Migratory File

Found corrupt jpeg file printed with different printing software

2016 - Ongoing