Why is this error (-50) coming up?

Had the same problem too about 2 hours ago, cannot open my Apple ID account from iTunes for Windows, but from iPhone everything works well. Just checked iTunes and everything looks fine.

I think the problem is on Apple's end, because I didn't change anything today.

I woke up this morning and gave it another try. I was able to log in and download. All seems fine now. I don't know what changed since I was asleep.

Apple probably fixed whatever was wrong. Folks that had issues last night, can give it a try this morning. See if it's resolved itself. When glitches like this are on Apple's end, doesn't matter what you do to your device....it's kinda like if a TV station is off the air, doesn't matter what you do to tweak your TV, it can't pull in a signal that's not there.

I HAVE FIXED IT!!!

I spent ages trying to find a solution to this problem and I eventually stumbled across it.

Step 1: Right-click the iTunes icon

Step 2: Click Run as Administrator

That made iTunes work perfectly for me! I am not sure yet as to whether this is just a temporary fix or if it will solve the problem forever but it's the best I could do.

Hope this helps everyone!