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Grabbing a small/thin pin and carefully probing inside the lightning connector may be a way that you can clean out the port. You would be surprised with how much lint comes out of the tiny port. (Be gentle as this is a rather delicate part).

If you are urgent for a quick fix, try the following;

1. Plug the phone into the charger and dismiss the error.
2. Turn off the phone.
3. Leave the phone on charge for a few hours.
4. Turn the phone back on. You phone would have charged up whilst powered off due to the charger providing the battery power. The phones OS would not of been able to by pass the error message.