Answer: Your device has a time synchronization error.
To solve this, get the device where your two-factor authentication application is installed and follow these steps:
- Open the two-factor authentication app
- Click at 'General'
- Click at 'Time and date'
- Click 'Set automatically'
In most cases, this solves the problem. However, sometimes it helps to restart your device.
Two-factor authentication gives you a new code every 30 seconds. If the device does not have the right time, it will give you a false code.