unknown error (-50)

i purchased a TV Series on iTunes the other day on my macbook air and was able to DL all episodes w/o any problems, today I've purchased another but can't download any. I checked on it after a few hours to see the progress just to see an error message saying:

"There was a problem downloading "TV SERIES". An unknown error occurred (-50). Please check that the connection to the network is active and try again."

I looked at some other threads and when posting this had to find what OS I'm using (El Capitan) and found my storage was full. In the meantime i basically emptied my device so i now have over 50gb available, i thought this may have fixed the issue but it has not (needless to say I'm not annoyed i deleted all my stuff).

There's no wifi connection problems at all...

Anyone have any ideas?