Are you connecting the camera directly to the computer? If you are try a card reader.
I am connecting my camera to the computer. I do not own a card reader.
unplug the camera
reboot the computer
plug in the camera
Ultimately you will be much happier using a card reader. Card readers are much faster in the file transfers, do not need special drivers, are far less error prone, and do not drain the camera battery.
Thank you I will try that and I will try to get a card reader. The only fear I have with a card reader is me going out to take pictures and not having a card in my camera , but it is a D7100 I have two, so that really should not be a problem.
It is just strange because 5 weeks ago I took a trip and 372 pictures went through fine, then the next week I started having this problem.
Another thing that can be happening here is the second part of the error message: "or the destination folder is not writable. (30)". If by any chance you are importing to an external disk, check the connection to it as this also could indicate problems writing to the destination folder. Often those are permissions errors but can also be triggered by bad connections (bad USB cable, unseated plug, etc.) to the disk you are copying to.
Second, you should be extremely careful using Nikon Transfer. There are MANY reports of it corrupting NEF files when using it to transfer files making them unreadable to anything but Nikon Software. In fact you should only use operating system utilities or Lightroom's import to transfer files. This is also why using a disk reader is a much better choice.
im having this issue with my card reader.
i bought a new one and stiil getting the error message was not imported because not able to read
tbray76, check the answers in this thread. This error is usually (and confusingly) caused by the destination folder where you are copying the files to not having write access for the user you are using. You need to check the destination selection in your import panel and make sure your user can write files there. Realize that on both Mac OS X and Windows you normally are not able to write any files in the root level of your hard disk so make sure it is in the user's home folder or an external drive that you are using.
All the above from Jao, and-
I have seen this error when someone is 'accidentally' trying to copy the photos from the camera card BACK to the camera card, and the card is full. Check your destination folder in the Import dialog.
This should not (or cannot) occur with recent versions of Lr, but check anyway.