How to approve iPhone if you have no other device? After upgrading to latest iOS I get a message asking to approve my phone from another device. 

Problem 1: I do not have another device. Is apple forcing customers to have more than one device? or how do i fix this? 

Problem 2: It also gives me a message, "Can't approve this iPhone". If I click there it warns you that the only way to continue will be by resetting all my info on iCloud which is something I DO NOT WANT to do.
I had the same problem.  I actually had an old ipod associated with my account that I didn't realize and had to remove it.
Go to: https://appleid.apple.com
And choose "Manage your Account".
Look at your devices and see if you  have any old devices.  If so, remove them.  That is what worked for me.