Never-ending loop on Mac with 2-step verification

Try doing exactly what the message says -- "enter your password followed by the verification code sent to your trusted device"

e.g., if your password is xyz and the verification code is 123456, enter xyz123456 into the password area.

The newer "two-step authentication" (not the older "two-step verification") requires that method of input on devices running older versions of the OS. Not sure why that would be happening in your situation but it is worth a try.

See the quote below from Two-factor authentication for Apple ID - Apple Support

If you use two-factor authentication with devices running older OS versions, you might be asked to add your six-digit verification code to the end of your password when signing in. Get your verification code from a trusted device running iOS 9 or OS X El Capitan, or have it sent to your trusted phone number. Then type your password followed by the six-digit verification code directly into the password field.

I struggled with this for an hour and saw several online suggestions. In the end I was able to solve the problem by going into the SETTINGS on the Apple TV and entering the credentials into iCloud

My pervious attempts all started when I tried to look at purchased movies. That's when I got prompted for the credentials and entering them ended me in an endless look.

When I went to the settings of the AppleTV and deleted my iCloud account then re-added it, I got prompted for the credentials once and then the movies worked as expected.

So, if you are having troubles with credentials on an Apple TV and stuck in a look asking for verification codes try removing your iCloud account and re-adding it. That's the only thing that worked for me.

Here is what worked for me. Click OK on the Mac when it does this. Then go to your iPhone and click Settings, Apple ID, Password & Security and then Get Verification Code. Make a note of the number you get. Go to your Mac and click System Preferences, iCloud and when it asks for your password type in the password immediately followed by the verification code you made a note of and then enter.

Thanks! This worked for me. I thought I was going nuts.

Apple really screwed up by appending to the usual error msg without pointing out that there was additional info required at the end of it... Those of us who've used macs for decades see these boxes so much that we don't always bother to read the entire msg. I'm guilty here, but why not split up the msg into two separate statements, or bold the difference between the normal msg and the new one. I remember when you could talk about an apple computer and not lie when you said, "it just works" ... 😟

Nope.
MacPro Late 2013 running Yosemite

iTunes 12.5.5.5
iPhone 6s with iOS 10.2.1

On Mac, open iTunes, go to Store tab, find album, click Buy. Asks me for Apple ID and password, I enter. The password field goes away and an Allow/Don't Allow message comes on my phone. I click Allow and get a verification code. No place in iTunes to enter it because the password field is already closed and has to be closed in order for me to get the verification code to enter into it. That's the hangup. If I refresh the iTunes browser, I can click Buy again to get a new field. But that generates a new verification process, so entering the code I have with my password doesn't work. I would have to go back in time with the verification code to enter it into the field that needs it.

I suspect that my problem may be related to the fact that I'm using my personal Apple ID for iTunes on my work computer, which uses a different login for the OS. But I have no way to test that theory. Anyway, I used to be able to buy music with iTunes on my computer at work, and it would conveniently populate my personal devices with the purchase, as well. Now I have to go about it the opposite way - buy the music on my phone so that it appears in iTunes on my work computer. Not the end of the world, but inconvenient.

Oh, dear. "That's not what we think design is. It's not just what it looks like and feels like. Design is how it works.”

Well Apple, this doesn't work.

Thanks to @FoxFifth. Now I only have to figure out why KeyChain requests an additional password (and four-factor authentication?), triggering a message with a code on the iPhone, and then just resulting in a "meh" on the Mac. So tired.

Appending the verification code to my password and then inputting that as my password worked for me.

However, this is breaking all sorts of UX norms. I can't describe how unintuitive and unexpected this method of inputing an additional code was. Please, please, please just add an extra field for the input of the code! Anything other than that is dragging the Apple experience in the direction of Windows. This wasted 10 minutes of my precious life that I will never get back!!!

This doesn't work for me. By the time I answer all the prompts and get half way through entering my password, the "Additional verification" dialogue appears again and I'm back to square one. I can't get through the dialogues and enter the password fast enough to beat the next one asking for a new code.

The only way I can stop this is to turn the iPhone off. Aggghhh!!

What version of OSX are you running?

Please, please, please just add an extra field for the input of the code! A

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