If raw files were fine after import (and I mean long enough after import that raw data was rendered by Lightroom, i.e. after initial view of embedded jpeg is replaced by Lr rendering), then went bad - it's probably due to a hardware problem, most often disk or ram. Unless it's gone completely bonkers, Lightroom doesn't write to your raw files, so doesn't corrupt them.
I am not talking about raw files. I believe I said "JPEG Marker Segment"? Some of these files were never even raw to begin with and many of them go way back to LR3. Why can't I get Adobe to talk to me about this. Not only are the files corrupting (luckily I have good backup practices so I can replace the files). I know it sounds impossible but Lightroom is actually corrupting the original file NOT the preview file. Why would it be doing this? The way I find out is if I go to move or copy the file to another location or use LR to import to another physical location. Not only are files corrupted but I am finding that the time stamp is being altered, too!
Sorry - jpeg then, not raw..
This is the user-to-user forum (which Adobe also participates in, occasionally).
You may (or may not) have better luck talking to an Adobe employee in the Adobe feedback forum:
And of course there is always customer service (e.g. chat) - set expectations low..
If I were you, I would:
* turn off auto-write xmp.
* make files read-only.
* discontinue saving xmp manually.
* compute checksums over all your files, using Raw File Integrity Checker (a free plugin I wrote, which works for jpegs too).
* check checksums frequently.
And then see what happens. If still having corruption, it's a hardware problem for sure.
If Lightroom is corrupting them, then it's probably happening whilst writing xmp, since that's about the only time it writes to those files, theoretically.
Note: just because they are getting corrupted on Lr's watch, does not mean the problem is due to a bug in Lightroom - if hardware problem during writing, that'll do it..
Anyway, RFIC will help determine where the problem is, and if there is a pattern..
Thanks Rob. Appreciate the advice.