That message usually indicates that you don't have write permissions for the destination folder. Check your permissions for the hard drive and the folder to make sure they are set to allow you to both read and write.
Thanks Jim, I don't recall anything about permissions on my previous imports. Can you tell me where permissions are please?
Check the destination folder specified at the right of the Import panel. his has either changed to something LR cannot write to—usually this is the problem, or the permissions on it have changed to due to an OS update or being logged in as a different user or something.
Changing permissions are an OS-level function not something Adobe software, so do a Google search for “change permissions” and then specify your operating system in the google query, like “Windows 8” or “OS X 10.10” or whatever and I’m sure you’ll find instructions.