Activation Lock is designed to keep the information of the iOS device safe in case it is lost or stolen. When your iPhone faces an activation error and says The iPhone could not be activated because the activation information could not be obtained from the device, it means that the activation information wasn't sent or received properly. This iPhone activation error can happen due to the following reasons:
1. You have a weak network so that the information of your device cannot be sent properly.
2. The assorted Apple service isn't running.
3. The carrier of your SIM card isn't supported.
4. Activation Lock might be enabled in Find My iPhone.
5. The iOS version of your iPhone is now unsupported by Apple Server.
6. iOS firmware was not installed properly on your iPhone.