I have had LR5 for sometime now and I have had no problems with uploading my files from my Canon T2i. I recently tried to upload several files and I continue to get the error message saying that "could not cop a file to the requested location" (that is if I try to upload one directly from my desktop) or it will say "The following files were not imported because they could not be read" if I try to upload it directly for my SD card. I have read other forums and I am not the only one who is experiencing this issue.
I recently updated LR5, I have also updated my Mac Book Pro.
I just purchased a new SD card that 32 mb 80MB/s. It is not the SD card either because I was able to import files from it a week ago.
Now it is saying that no photos or videos were found to import and I just tried uploading another test file from my desktop!