Recovery Key for iCloud

If you have 2 Step Verification enabled on your ID, see the article below.

Apple ID - Two Step Verifications FAQ    

If you have 2 Factor Authentication, enabled on your ID, see the article below.

Recovery key for 2 Factor Authentication no longer exists.     

If you have tried using a verification code for iCloud and it didn't work, I suggest you contact Apple ID Support for assistance. Something doesn't seem to be working correctly. See the Apple Support articles below for contact information.  

Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.   (Link doesn’t always load)  

Get Support          Work through the screens to get a chat option. You may have to pick a slightly different problem.

Apple Support schedule phone call

https://twitter.com/AppleSupport.          People have posted it may take an hour or more to get a response.

Then that means your AppleID is not using 2 factor authentication, but is still using the older 2 step verification. 2FA has no recovery key, and when you change your AppleID from 2SV to 2FA, the recovery key no longer has any meaning or use with your AppleID.

So you will likely need to go through Apple’s AppleID account recovery process to regain access and control of that AppleID -> Recover your Apple ID when you can’t reset your password - Apple Support

Any device running older versions of OS X or iOS work that way -> Two-factor authentication for Apple ID - Apple Support

"What if I use two-factor authentication on a device running older software?

If you use two-factor authentication with devices running older OS versions—like an Apple TV (2nd or 3rd generation)—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 and later or OS X El Capitan and later, 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."

Is it asking for a recovery key, or a 2FA code? If your AppleID is using 2FA, then the 2 step verification recovery key no longer exists as it doesn't apply.

But if you're getting a 2FA code on your other trused devices, use that and enter it right after the password e.g. password123456, no spaces).