When uploading many files at once (a CMS, for example), it is not uncommon for a few of the files to fail the FTP transfer. This will often happen if there are many FTP connections going to your server. If a transfer fails, simply restart the transfer for those files and they should complete the upload process.
If you are uploading a large number of website files we always recommend you archive the files into a .zip, upload the zipped file, and then extract it into the correct location on the server. (The extraction will need to be completed use the file manager which can be found in your control panel). This has 2 advantages. Not only do you greatly reduce the risk of individual files failing to transfer, you will dramatically increase the speed in which the files transfer as only 1 single connection is required.
