I have been lately shooting some photos with my old Canon 450D (or Rebel XSi) in RAW+JPEG mode and then trying to edit the photos in Lightroom 6.0. I've tried importing the photos to Lightroom both from the Photos app (on macOS Sierra, by exporting the unmodified originals) and straight from the camera, but will always only get an error message saying
The files are not recognized by the raw format support in Lightroom. (90)
I then tried taking a photo in RAW-only mode and importing it straight from the camera, and that seemed to work fine.
So, are the RAW files saved in RAW+JPEG mode somehow different from the files the RAW-only mode generates? Or why is Lightroom able to read one of them but not the other?
I've also tried deleting the accompanying JPEG photos from the directory that I'm importing the RAW photos from and setting the option "Treat JPEG files next to raw files as separate photos" in Lightroom preferences but still get the same error.
Edit: It seems the free Adobe DNG Converter has the same problem, i.e. it doesn't open those CR2 files created with RAW+JPEG mode on.
Edit #2: I now noticed that the RAW photos exported from my camera have the exact same size as the corresponding JPEG files. So the problem must be in the camera or the memory card and isn't related to Lightroom at all.