This warning message appears in the log file when a file has been deleted (or an attempt to delete has been made) using parallel worker threads (see Number of files to delete in parallel setting in Copy/Delete->Advanced) but has not been processed. This happens when the profile is aborted. With parallel file deletion, many files are being deleted at the same time they are being copied. At some point during the profile run, the result of that deletion will be checked and logged. If the profile is aborted before then, then it the result of that deletion has not been checked and processed, hence the warning message in the log file.