How To Fix Constant Apple ID Verification Password Pop-Ups on iPhone
From time to time, you might be experiencing an “Apple ID Verification” popup, which prompts you to enter your password. This can be a confusing experience when you are unsure of the cause of the issue and your iPhone keeps asking you to verify your Apple ID repeatedly. It then turns into a frustrating experience when none of the suggested steps resolve the verification trouble, because you cannot log in to your iCloud account. If you are affected by any of the above issues, see this handy troubleshooting guide.
First of all, check if you have an iOS update available by going to Settings > General > Software Updates because the issue in question is primarily affecting users on iOS 9.1, which is outdated at this point. This might already fix the issue for you. If not, keep on reading.
Apple ID Verification: What you can do about it
If you get this popup on your Home Screen or Lock Screen, try entering the iCloud password for your account to resolve the issue. If the login fails for some reason, you will have to resort to the following troubleshooting steps.
1. Logging out of your iCloud account
Log out of your iCloud account on all connected devices. Simply go to the Settings app in iOS and tap iCloud, then scroll down and sign out of your account. Repeat this on all mobile Apple devices you own.
On your Mac, if you have one, go to System Preferences and click iCloud, then signout of your iCloud account on that machine as well. Repeat for any additional Mac desktops or notebooks. Make sure that none of your devices are logged in.
2. Unlink / delete devices from your Apple ID
Next, go to the following web address and log in using your Apple ID, then check out the list of Devices and View Details for each of them.
Remove them from your account until no devices are left. If you are using Two-Factor-Authentication, you will have to perform additional steps to confirm your identity.
3. Log in to your iCloud account
Now you can log back into your iCloud account on all of your Apple devices. The error message should be gone now and hopefully stay gone.
Last resort: Reset your password
If the above steps did not work for you, it is time to request a fresh password for your Apple ID, which you can also get on https://appleid.apple.com/, where you can click Security and change your password from there.