Why is my transfer returning to a 404 error?

You've just made a new transfer and by trying to access to your transfer link from your history of transfers in your account, but you're unfortunately redirected to a 404 error page. 

This page probably means an issue happened during the upload of your files. 

This issue blocked the completion of the transfer, that's why the transfer link refers to a 404 error. 

Unfortunately we can't re-establish the status of this link. 

The only solution is to make a new transfer with the affected files. You can find some suggestions in this article.