If you can't send a file to one of your contacts, first make sure that you have exchanged contact details with the person to whom you’re trying to send the file. You can only send files to contacts who already accepted your contact request.
Also make sure that you’re sending files in the correct way. Learn more about sending files using Skype.
The problems with sending files through Skype may be caused by a slow internet connection. There are several reasons why your file transfer speed may be slow:
The transfer may be being relayed through another computer which is slowing it. A relayed transfer means that you’re unable to make a direct connection with the person you’re trying to send a file to. This may be caused by the settings of your firewall or router, or that of your contact. Learn more about updating your firewall to work with Skype.
If the problem you’re experiencing relates to the router, contact the manufacturer.
Either you or the recipient of the file may not have enough bandwidth available. Try closing applications that might take up bandwidth to speed up the file transfer.
If you’re currently on a Skype call, Skype will prioritize voice over the file transfer so that your conversation is not disrupted. The file transfer speed will improve when you end your Skype call.