Have you ever tried to upload to YouTube via the PS4 Share button only to get a “Can’t Upload to YouTube” error message? This has happened to me several times in the past with no clear answer as how to solve the error. There are several different methods I’ve come across on the Internet, such as logging off your YouTube account and logging back in again, but this doesn’t always work.
The last time I got this error, a quick search came up with someone suggesting that it’s because the upload notifications section is full. This seemed like an odd thing to suggest but checking my upload notifications did yield a fair amount of old notifications. After a few minutes of clearing out about 100+ notifications, a quick check to see if I could upload to YouTube proved to be successful! Not sure why this worked, but it did. I’m now able to upload to YouTube again and just to be on the safe side, started to delete old upload notifications more often as to not run into this problem again.
I can’t guarantee however that you’ll have the same success, but this seemed to do the trick for me so give it a try.