A few months ago, I switched from primarily using a mid-2009 Macbook Pro to a late-2014 Macbook Pro. Since then, I have been unable to import .NEF files from my Nikon D90 SD card directly into Lightroom (it looks like it's going to work, and then I get error messages saying "files were not imported because they could not be read"). This happens in both Lightroom 6 (perpetual license), and my older version of Lightroom 3, so I assume it has something to do with the computer. Any ideas?
The most common cause of the "could not be read" error is a need for WRITE access on the destination folder. Use Finder to see what your access level is.