Error message appears on source agent in transfer jobs - Distribution or Consolidation. It means that the mentioned files changed on source agent during transfer and the file is no longer the same as it was when agent indexed it. Or the files were permanently deleted.
Note, if a file is "moved" outside of the source folder but remains within same drive or partition, it will be downloaded by the destination, since the source Agent still keeps the handle to the file. If the file is permanently removed from the drive, the job run will stop (if "Skip file errors" parameter is False) or continue (if "Skip file errors" parameter is True). This is valid for FAT32 / NFTS and ext2/ext4 file systems. Other file systems may have their own peculiarities in this regard.
To fix it restart the job.
Watch that the files are not changed on source until transfer's finished.
Another possible solution is to enable "Skip file errors" in Agent profile. The Agent will ignore the file error, will not report the error in the job run, but will record event "Path skipped" in the job's log. The job run won't be aborted. The side effect is that files count on the job run may differ for source and destination agents even though they will report that they have successfully completed the run
Error code SE_FS_FILE_WAS_MODIFIED