When attempting to burn a CD with iTunes you may receive the below error.
ERROR: The attempt to burn a disc failed. An unknown error occured (-50)
If you do receive this error check and make sure that the playlist isn’t longer than the amount of room on the CD. In my case I noticed this error and one of the songs had an odd problem that made it show over 780 hours in the playlist however when playing the actual song it was only 3 minutes long.
Removing the song from the playlist you are attempting to burn and then starting the burn process again you should be able to burn the CD without issue.